Riku

"Come on now. Weren't you listening?... I absolutely loathe the Four Perils. The only time I'd be willing to take a life is if I'm taking it from someone that I love."

- Riku to Jyūbei

is a character in Hanyō no Yashahime. He is a mysterious young pirate and the financier of Shikabaneya, a demon bounty-hunting business owned by Jyūbei, the corpse dealer. In truth however, he is also a retainer and the first daiyōkai incarnation of the qilin daiyōkai Lord of the Eastern Lands Kirinmaru and his older sister Zero. Seeking to return the Rainbow Pearls to his madam Zero, he secretly manipulates the three half-demon princesses into eliminating the Four Perils for him. As time passes, Riku develops a strong interest in Towa Higurashi, the hanyō daughter of Sesshōmaru and Rin. As his fascination with Towa grows, Riku comes to fall in love with her, causing him to be an occasional ally of both her and her family as they seek to defeat his former master.

History
Riku was born around 600 years ago from Kirinmaru's left horn after it was broken off during a battle between Tōga and Kirinmaru. After his creation, he was raised by the demon lord's older sister Zero while also becoming his creator's most trusted servant, he heard to dispatch the arm because the bugs seek demon energy are such a nuisance, then he ask where to dispose it, and Zero answered the Bone-Eater's Well at Musashi Province. When Kirinmaru received word that his rival Tōga, the dog-demon ruler of the Western Lands, had received fatal injuries during an epic battle with the dragon-yōkai Ryūkotsusei, he tasked Riku with gathering medicine: the medicinal herbs to save him before his impending death to heal his wounds from the battle with Ryūkotsusei. Though Riku managed to acquire the medicinal herbs needed to save Tōga's life, he arrived too late; the Great Dog Demon having sacrificed his life to save his human lover Izayoi and their half-demon son Inuyasha in a final battle with the human samurai lord Takemaru of Setsuna. By the time Riku arrived, Izayoi's mansion was already set ablaze as the villagers witnessed saw across the lake, and Tōga and Takemaru are dead inside, which means that he realized that he was too late. When Riku delivered news of Tōga's death to Zero, who was secretly in love with her brother's rival, she was so overcome with grief that she made a desperate wish upon the sacred Shikon no Tama to be rid of her grief forever. Watching her as she made this wish, Riku would witness the creation of the seven Rainbow Pearls, which contained Zero's lost emotions within them.

Sometime later, Riku became a pirate though he set a standard of never robbing women, children, or those in need. While it's not known when he first met Jyūbei, he became his patron and the main financier and client of his demon bounty hunting business, gaining his respect and loyalty by using his powers to reward him with much wealth.

Personality
Riku generally is a very friendly and easygoing individual despite being a pirate. He possesses gentlemanly mannerisms and speaks in ways that are sophisticated yet warm and welcoming to people he has just met. However, this affable nature appears to hide an unknown true nature and agenda which he masks behind a face of friendliness and optimism. Riku also seems to possess rather mixed views regarding humans. Despite remaining civil with them, he harbors the belief that no good can ever come from loving a human, only destruction. Despite this, he later calls humans beautiful creatures, due to the how quickly their lives and existence comes to an end. He also doesn't bear any ill feelings towards half-demons, despite believing the cause of their existence is dangerous and should be avoided.

Although he is capable of handling things on his own, he will not act unless it is something that he wants to do personally, preferring to let others unknowingly take care of those problems for him. He is shown to be a master manipulator, playing both the Shikyō and the half-demon princesses into doing his dirty work and benefiting off of their success and failures without them even knowing. He has also shown himself to be a bit sadistic as well, as seen when he smiled in satisfaction as Homura was burned alive by his own rage. He also seems fairly bloodthirsty, enjoying the thrill of fighting with a powerful opponent.

Despite his manipulative nature, Riku does reward those that aid him, as he is the one that has been hiring Moroha to kill various yōkai for him, paying her through Jyūbei. He also fairly rewards Jyūbei himself, using his earring to create gold in order to pay his servant.

He also seems to be very knowledgeable about important events, telling the audience, as a fourth wall breaker, the story of what happened until Episode 15. He warned Kagome about the Grim Comet and Kirinmaru wanting to kill her child and the half-demon twins. Apparently, he also knows that Towa, Setsuna, and Moroha are granddaughters to the Great Dog Demon as he addresses them as "Half-demon princesses". He is aware that Towa inherited her father's Sōryūha.

Riku also seems to have an interest in the subject of love, though it seems he has been unable to truly grasp it. In his concept, to truly love someone means killing them. During the flashback opening of Episode 21, it was shown that 200 years ago, Riku possessed a much different personality. He was shown to be practically emotionless and somewhat less intelligent as he was unable to understand basic concepts and suffered misunderstandings from the words of others. He seems to have taken an instant interest in Towa, befriending her shortly after meeting her and keeping a close eye on her in order to observe her new abilities. However, he has expressed disappointment in her skill with her blade in comparison to her father. Despite this, he seems to be keeping an eye on her progress in developing her powers. This interest in Towa grows deeper, as he develops a strong liking towards the kindness, sincerity, and compassionate heart she has gained from having been raised in the modern era. Eventually, this interest into her character evolves into an attraction towards her, causing him to be quite affectionate and even flirtatious, bordering on seductive, towards her. Despite still wanting to take the Silver Rainbow Pearl in her eye, he wanted to have a "date" with her first and made it clear that he wanted to take it without hurting her. He is even willing to go to great lengths to protect Towa from danger and even despair. When Tōtetsu attacked them, not only did he risk his life to protect Towa but he was also willing to sacrifice himself so that she could escape. He even betrayed Kirinmaru, his former master, in order to help ensure her survival, showing that his feelings for her have grown stronger than whatever loyalty he once held to the demon lord. He also tried to protect her sister Setsuna, even lying to his madam Zero to do it, since he knew how much Setsuna's death would break Towa's heart.

Physical description
Despite being a demonic incarnation, Riku is physically identical to the humans. He is a handsome young man with slightly tanned skin, green eyes and chin-length auburn hair, with part of it styled into a Japanese topknot, as well as two long bangs along the sides of his face. He also has a violet stripe on each eyelid.

Upon being blinded by Kirinmaru, Riku's eyes have briefly taken on a shade of purple with sparkles. After applying hand cream, his eyes take on a more lavender hue to their color.

Outfit
Riku wears a striped blue and dark blue kosode with torn edges along the sleeves, a white hadajuban undershirt, a beige haori with red and black stripes along the collar, a light blue sash tied along his waist, grayish purple hakama leggings with thin vertical dark grayish purple stripes, a pair of black suneates around his shins, a pair of white tabi on his feet with waraji straw sandals, and usually a yellow furoshiki with black details which is tied over her shoulders.

Later, Riku wears a black haori with red and yellow accents, a striped blue and light blue kosode which is more neater, and grayish blue hakama leggings with thin vertical dark grayish blue stripes.

He wears a round blue earring on his left ear. Later, under a round blue earring, he has a sword earring.

Powers & Abilities
Although not much is known of Riku's abilities, he is regarded as being an extremely powerful individual, acknowledged by Jyūbei and Takechiyo as being a powerful lord, and being deemed capable of easily killing the Shikyō if he actually desired it. Even the extraordinarily powerful demon Kirinmaru, the Ruler of the Eastern Lands, shows great faith in his abilities, Riku being his most trusted retainer.


 * Great Physical Strength: He has displayed remarkable levels of superhuman strength to easily overpower Tōtetsu, the largest of the Four Perils, casually maintaining a blade-lock with him despite his much larger size and sword and able to easily hold his mouth open to prevent him from devouring him and kick him with enough force to stagger and knock him down, even able to throw his sword with enough force to decapitate him.
 * Great Durability and Endurance: Riku was resilient enough to survive being impaled by Tōtetsu's projectiles with only little pain and minor bleeding.
 * Great Speed, Agility and Reflexes: Riku has displayed great speed, able to easily keep up with and pressure Setsuna in a fight despite her own impressive speed.
 * Master Hand-to-Hand Combatant: Despite rarely fighting, Riku proved to be an excellent warrior in his own right when pushed, displaying remarkable skill with both hand-to-hand combat and swordsmanship, able to make short work of Tōtetsu and quickly push back Setsuna in close combat.
 * Longevity
 * Levitation: Riku is capable of levitating himself off the ground and remaining suspended as well as flying through the air at incredible speeds with ease.
 * Ash Demonic Shield: Riku use the fully demonic-empowered ashes of Tōga to protect his "madam" Zero from Moroha's Crimson Backlash Wave.
 * Hydro-Cryokinesis: At one point, he utilized his elemental abilities over water to freeze the surrounding sea into solid ice to save Towa from falling prey to the inconsolable snake-demon spirit from afar.

Weapons



 * Earring: His main weapon is a little round deep blue earring on his left ear, which he eventually added a gray sword-shaped earring underneath. Some of its demonic abilities are:
 * Matter Alteration & Transfiguration: By flicking his earring, Riku can alter and control any form of matter (both organic and inorganic), such as manipulating water (boiling water in Episode 21), producing gold dust and even disintegrating living beings like Kyūki.
 * Summoning: By touching his earring, Riku is able to call Takechiyo at his command and also summon miasma bug. In Episode 29, Riku flickering his earring to summon a boat.
 * Teleporting: By flicking his earring, he can transport from one place to another.
 * Sword: By flickering his earring, Riku summoned his own weapon his sword when he fought Tōtetsu during the night of the new moon to protect Towa. Until he left it and broke it while used by Kirinmaru.
 * Sword-Shaped Earring: As of the second season premiere, he has the second sword as an earring, and in Episode 27, he flickering his earring to summon his second sword to kill all three Ogres and one have the green Rainbow Pearl in his right eye to save Setsuna. In Episode 43, his second sword changes from the sword to Zero's staff while he was fighting him at the Windmill of Time.
 * Kikujūmonji: He possessed the genuine Katana shortly, after stealing from the Deputy Shogun of Kanto, but did not express any desire to utilize it since it was forged by mere human men.
 * Zero's staff: He had managed to pull it out of his body and wield its abilities to get Rion back from her father's clutches by wrapping her unconscious body in a cocoon of spider silk.

Weaknesses

 * Blindness: Following an encounter with Kirinmaru, Riku became blind from Kirinmaru's exit.
 * Linked Fate: Being an incarnation of Kirinmaru, Riku would unfortunately perish if Kirinmaru is slain.

Relationships

 * Towa Higurashi

Riku and Towa have their first encounter when Towa heads outside to look for Mount Musubi and the Dream Butterfly in Episode 7. When Riku approaches Towa is she instantly on alert and on guard, but Riku assures and promises Towa that he doesn’t mean anything suspicious. Riku initially mistakes Towa as a samurai, but later calls and addresses Towa as "hime-sama" meaning princess and Towa-sama (Lady Towa). Riku quickly tries to befriend Towa and wants to gain her trust. Riku ask Towa to help him with finding his ship since both of them appear to be lost. Towa later leads him to a river where Riku shows his ability in manipulating water, using his blue earring. Towa is immensely impressed and Riku says that anyone can do it with a little bit of concentration. Towa then invites Riku to a picnic with modern food. Riku takes a bite of an apple and remarks the apple’s delicious flavor. After a lunch break, is Riku seen leaving on a boat after thanking Towa for her kindness. Riku leaves behind a stolen katana from Ogigayatsu Hiiragi Danjo as a parting gift for Towa but she later ends up being captured as a culprit by Yotsume disguised as Sōkyu.

Riku immediately seems to have a significant interest in Towa and says in a conversation with Jyūbei that he likes her, considering her to be a "fine young woman". Riku is almost always seen having a kind and curious approach towards Towa, wanting to know her opinions on different situations. Riku is also aware that Towa is Sesshōmaru's daughter, implying his interest and recognition in her. Riku even stated that Towa inherited the Azure Dragon Wave from Sesshōmaru. In private however, he mockingly expresses disappointment when her power proves inferior to her father's. Despite this, he still possesses a significant interest in her development as she slowly becomes stronger. He also, unlike others, shows a fair amount of patience and amusement with the habits she exhibits from living in the modern world, even though he doesn't truly understand what they mean sometimes. In addition, Riku seems to be fascinated and touched by the kindness and compassion Towa exerts from having lived in the Modern Era. By the time of Episode 21, Riku's interest and fondness for Towa seems to have turned into a genuine attraction for her. When Riku decided the time had come for him to collect Towa's Rainbow Pearl he confronts her on a night of the New Moon during which her powers fade and she becomes fully human. Rather than simply taking it from her by force however, Riku remained polite and civil towards Towa, even calling her "exceptionally beautiful" in her human state and gently caressing his fingers upon her extended hair. Towa was visibly flustered by Riku's advances and compliments, unaware that he was planning on taking her Pearl. Riku afterward has tea with Towa and shares his knowledge of the Rainbow Pearls with her. Riku also talks about a madam and a master that he is under. Riku later mentions to Towa that he wants to assemble all the seven Rainbow Pearls, including Towa's, Setsuna's, and Moroha's Pearls and return them to the madam. When Towa realized this, she prepared to fight Riku just as he attempted to take the Silver Pearl, painlessly, out of her left eye. Before he could though, Tōtetsu, the last surviving Peril, suddenly arrived and attacked Towa. Though they both served Kirinmaru, Riku was angered over Tōtetsu ruining his "date" with Towa (seemingly more so than foiling his attempt to steal the Pearl) and chose to defend her from the gluttonous demon, risking his life and shielding her with his own body, which left him critically injured. He also appeared surprised and somewhat touched when she refused to leave him and was worried for his condition despite briefly being enemies but moments ago. Taking a moment to rest, Towa questioned Riku on why he would protect her when she is an enemy of his master. In answering her, Riku partially revealed his feelings of love for Towa which left her shocked and caused her to blush. When Tōtetsu eventually found them again, Riku urged Towa to runaway and save herself, showing that he was willing to sacrifice his life for her despite still wanting the Silver Pearl inside her eye. After Riku killed Tōtetsu and Towa had regained her demonic powers, he hugged her and took great relief in her safety, much to her shock and fluster. In gratitude for saving her, Towa handed Riku her Pearl though she quickly regretted this when she remembered he worked for Kirinmaru.

Based on his conversations with her regarding the nature of love, it is heavily implied that Riku has fallen in love with Towa. Even though they are now enemies, Riku still continues to worry about Towa and even somewhat looks out for her. He seemed saddened at the thought of having to fight Towa and was even willing to lie to his madam, Zero, about how to unlock her true powers. Despite this, he is willing to fight her if he has to, with Setsuna noting during hers and Riku's duel that she is the one he truly wants to face. Riku describes Towa as "too kind for her own good".

In Episode 24, it is revealed that Riku orchestrated the battle between Towa and Homura in order to discover the way to unlocking her true inner power. From observing this battle, he was able to ascertain that Towa's powers can only be unlocked when her sister Setsuna is either in danger or killed, something he apparently told Kirinmaru. Realizing how much grief and the sheer pain her sister's death would cause her, Riku attempted to lie to Zero that Towa had no hidden powers, though his effort did not fool her. This shows that Riku genuinely cares about not only about Towa's well-being but also her happiness as well. He also openly considers Towa to be the "nicest person" and even kept her in his thoughts before the coming battle between her and Zero. In fact, Riku even went as far as to betray Kirinmaru and stab him to weaken him enough, not only to allow Zero to escape her brother's wrath, but to also give Towa a chance to defeat him or at least survive, showing that his care for her was enough to exceed even his loyalty to Kirinmaru. Towa, in turn, was touched and appreciative of Riku's gesture, while silently lamenting that she was saddened for only being able to talk to him for a short while. Since Towa stab Kirinmaru on the same spot as she tells him, "Riku, you left a nice wound to exploit. I'll use it to my advantage!"

Riku later assists Towa from the shadows in her combat against the female serpentine demon by utilizing his elemental ability over all states of Water; he froze the sea over. From afar, he admitted that he was glad that she had survived and silently encouraged her to find a mystical Kyūyōkon Root that would greatly increase her chances in defending herself and her loved ones in the battles yet to come. By this point, Riku seems to have made protecting Towa one of his primary concerns, feeling that Towa's sister Setsuna is not strong enough to ensure her safety. Because of this, he dubs himself Towa's "bodyguard" and continues to watch over her from the shadows.

On the Half-Demon Princesses' way back to Kaede's village with Rion from Mount Musubi, Towa saw Riku on the mountain corpses of ogres and saw Rion on Towa's back. He revealed that everything he see and hear gets back to Kirinmaru which makes Towa surprised. Following the meeting with Rion, Riku hoped that seeing her face would change his Madam's mind regarding her desire to eliminate Sesshōmaru's twin daughters. Much to his dismay, however, Zero, realizing his feelings for Towa, intended to spitefully take her life to make Riku suffer. Riku and Rion both decided to protect Towa together. During this time, Riku was blinded from an attack from Kirinmaru while protecting Towa. Even though Towa was partly responsible for the loss of his eyesight, Riku held no anger towards her, instead regarding it as a small price to pay for protecting her. Riku would later use some of Towa's lavender hand cream to heal his eyes, after which Riku revealed that Towa was the only person he could see from now on. Hearing this caused Towa to blush.

Knowing his fate, Riku claimed that Towa had helped him understand the feeling of falling in love and had given him a reason to live. Riku even decided to put his artificial life on the line to ensure Towa's kon is not drained dry.


 * Setsuna

As the daughter of Sesshōmaru, Riku seems to respect Setsuna, though he doesn't take an interest in her as he does towards her sister Towa. Towa introduced her sister and Moroha to Riku shortly after their battle with Kyūki, unaware that it was him who actually finished her off. Though they meet a few more times, usually when he gives them an assignment, Setsuna doesn't talk to him much and seems to be fairly neutral to him, not suspecting that he is, in truth, seeking to steal her Rainbow Pearl. Episode 21 when he hugs Towa, she threatens him with her naginata, because he has the same scent as Kirinmaru. Though he found her comment "tasteless" and was bothered by her interruption of the tender moment he was having with her sister, Riku let it slide and left without fighting. Setsuna appears to be aware of Riku's romantic affections for Towa, but doesn't approve of them due to him being the retainer of their enemy Kirinmaru.

In Episode 23, when Setsuna comes seeking revenge on Zero, Riku's madam, she ends up running into him instead and the two fight, with Riku proving to be more than a match for her. Riku was later horrified when Setsuna struck down Zero with her Blood Blade attack, but did not seem to bear any grudge against Setsuna after her father revived his madam. It is also revealed in Episode 24, that Riku, in truth, doesn't wish any harm to come to Setsuna, knowing how much this would hurt her sister. When Zero inquired about how to unlock Towa's true powers, Riku, knowing that the only way to achieve this was by either hurting or killing Setsuna, attempted to lie in order to protect her and thus spare Towa from the grief and pain of her death. Despite this, Riku doesn't not actually care about Setsuna herself, claiming the only reason reason he is helping her is because he doesn't want Towa to be saddened.

In Episode 27, Riku and Setsuna meet again after he helps her defeat a group of Oni attacking her. Despite this, Setsuna still doesn't approve of Riku being around Towa. Riku does not approve of Setsuna either, and believes he should be the one protecting Towa, since he feels Setsuna is far too weak to do it herself. Though Setsuna is still weary of him, she agrees to let him help her, Towa and Moroha in their journey, since he genuinely loves and wishes to protect Towa. In gratitude, Riku gives her a map leading to Bokusenō's location before disappearing.


 * Moroha

Moroha has to kill the Four Perils as a bounty hunter for Riku, so she cares more about his reward. Even if the quest is a trap. Moroha calls Riku a fine man because she receives Tōtetsu's head after Riku killed him.


 * Jyūbei

Riku is the patron of Jyūbei's demon hunting business, with Jyūbei receiving the quests that Moroha has to perform. Jyūbei has been shown to be quite loyal and grateful to Riku for his generous donations of wealth. It is worth noting that Riku is the person that Jyūbei has been shown to be the most respectful and humble towards, addressing him as "Lord Riku" and even bowing to him. Riku, for his part, seems to consider is quite civil of Jyūbei and seems to hold him in fair regard. Riku always rewards him generously for his servitude by using his magic earring to create large amounts of gold dust for him to have. It is yet unknown how long they have known each other, but at one point in the past, Riku gave Jyūbei the Green Rainbow Pearl, showing that he has a fair amount of trust in him.


 * Takechiyo

Takechiyo addresses Riku as "Lord Riku" and follows the order to transport him and the Half-Demon-Princesses when its needed. Takechiyo doesn't seem to realize Riku's plan to lure the girls in a trap.


 * Sesshōmaru

While it's unknown if they have met, Riku has been shown to be very knowledgeable of Sesshōmaru and holds him in high regard. He seems to possess knowledge of Sesshōmaru's powers and abilities, such as the Azure Dragon Wave attack. He also has a particular interest in his daughters, particularly Towa whom he seems to have feelings for. Due to his respect for Sesshōmaru's power, Riku seems to place high expectations on his daughters, voicing his disappointment when they fail to live up their father's reputation. Despite his respect for Sesshōmaru, Riku is not without his criticisms of him, believing his decision to mate with a human like Rin to be foolish and inviting of nothing but destruction.


 * Tōga

While it's unknown if Tōga and Riku met when the former was still alive, it is shown that the latter holds him in high-regard. It was later revealed that Riku was charged by his master, Kirinmaru, with saving Tōga after he had received lethal injuries from his epic battle with Ryūkotsusei in the valley. Under his master's orders, Riku gathered the medicinal herbs needed to save Tōga's life, but did not arrive in time to treat him before his flight to rescue his lover Izayoi. Thus Riku's failure inadvertently resulted in Tōga's demise in his final battle with Takemaru, as well as his madam Zero's decision to use the Shikon Jewel to purge her emotions. Despite Tōga having been dead for over 200 years, Riku continues to hold the fallen demon-lord in high regard and respects those who come from his bloodline.


 * Kagome Higurashi

They first met during the night of the lunar eclipse, shortly before the Grim Comet traveled close to the earth and warns her about it. When he states that Rin will give birth to twin hanyō daughters tonight and Kagome is pregnant and that her quarter-demon child will be in danger should Kirinmaru wake up from his slumber, she quickly trusts Riku's words and warning her friends, husband and half-brother-in-law about Kirinmaru's plans against their unborn daughters.


 * Kirinmaru

Riku is a part of Kirinmaru, therefore Kirinmaru can see and hear through Riku because they are from the same body. To some point in the past he was Riku's master, until Riku did something yet unknown that Kirinmaru and his follower couldn't forgive. Then Kirinmaru summoned him to gather the medicinal herbs to heal Tōga's wounds from the battle with Ryūkotsusei. So Riku went his own way. Kirinmaru still seems interested in Riku's actions, stating to Zero that he trusts him with an not nearly described matter.


 * Zero

She cared for Riku after his creation, possibly causing him to see her as a mother-figure. However, after receiving news of Tōga's death, she appeared to be somewhat verbally abusive towards him, which could have possibly been caused by his emotionless attitude or him being unable to arrive to Izayoi's mansion in time, which could've prevented Tōga's death. She appears to still hold him in disdain after all these years, but despite this, she does continue to let him serve her and does at time admit when he has proven useful. Riku seems to be very loyal to her, as he claims to be collecting the Rainbow Pearls for her. Despite this loyalty however, he is not above going behind Zero's back. This can be seen when he didn't tell her he had most of the Rainbow Pearls till the attack on mansion when all seven had been gathered. He is also willing to deceive to Zero, as he lied to her about how to unlock Towa's hidden powers, even though she wasn't fooled. Riku still cared about her a great deal, attempting to serve as something of a conscious to her when she is angry or makes rash decisions. Riku was horrified and heartbroken when Setsuna killed Zero with the Blood Blade, to point of near tears, and was visibly relieved when she was revived by Sesshōmaru's Tenseiga.

After reclaiming the scattered Rainbow Pearls, Riku was crushed when Zero told him to leave her sight as his presence only transmitted to Kirinmaru. Zero is aware that Riku has fallen in love with Towa, whom she wishes to kill in order to make Riku suffer out of petty spite towards Tōga rejecting her. As a memento, he later utilizes her spider staff to get Rion back from Kirinmaru's grip on her.


 * Rion

His relationship with his master's only child is akin to a strong brotherly-sisterly love, as she had witnessed his formation from her father's broken right horn into humanoid form six centuries ago. Since finding her "alive" in an artificial body constructed of bones and grave soil, he happily ran to her and hugged her, amazed at how she had escaped Mount Musubi after so many years. Not wanting her to become a burden to Towa, he offered to be her bodyguard.

When Kirinmaru eventually appeared to replenish Rion's haku within her counterfeit body, he was not amused at the beast king's desire to chat as time was of the essence. Upon learning that Towa was in mortal peril from the curse upon the Zanseiken, he told his former master at how sacrificing Towa was something he could definitely not overlook and challenged him to battle. His sword was soon knocked from him and rushed to Rion's aid, only to be mortally wounded by Kirinmaru placing the spider staff Rion now wielded right through him. Fortunately, he managed to pull it out and use said staff to get Rion back by encasing her unconscious body in a cocoon of spider thread.


 * Kyūki

While Riku and the Four Perils share mutual animosity towards each other, Kyūki seems to loathe him the most. Her disgust towards Riku can be seen from her frowning whenever he is within her presence. Riku's also seems to hold Kyūki in low regard, seeing her as weak and pathetic. While he is aware of her plans to overthrow their master one day, he shows no concern over it, believing her to weak to accomplish such a task. After she is defeated by Towa's Azure Dragon Wave, Riku appears before her. As she lays beaten on the ground, Riku chides her for being defeating by Towa's "half-ass" attack, showing his disgust and contempt for the winged-demoness, all the while preventing her from reaching her rainbow pearl. Having no more use for her, Riku decided to finish her off himself. Kyūki's uses her final breath to curse Riku's name before he reduces her to dust and bones, taking the demon's Purple Rainbow Pearl for himself.


 * Konton

They meet up in Episode 17, where Riku went to a cave to support Konton luring the Half-Demon Princesses into a trap. Konton doesn't seem to trust Riku fully, because he states that Riku wasn't helpful in the past, but still accepts his help. After Konton is defeated in Episode 18, Riku is looking at the headless corpse without a word and takes the Blue Rainbow Pearl with him. Riku has stated that he hates the Shikyō for having poor taste.


 * Tōtetsu

Like with the other Four Perils, Riku and Tōtetsu share a mutual dislike towards one another, though both are usually forced to tolerate one another as they both serve Kirinmaru. Despite his loathing towards the Peril, Riku is capable of admitting when he can prove to be useful in his schemes. He offers the gigantic glutton as a focal point for Konton's eight field trap for the Half-Demon Princesses. Riku eventually becomes displeased when Tōtetsu appears to attack Towa, who had become fully mortal due the new moon, while Riku was attempting to take her Silver Rainbow Pearl. Furious over his "date" with Towa being rudely interrupted because of him (seemingly more so than foiling his attempts to get her pearl), Riku's hatred for the enormous glutton grows to point where he attempts to kill him with the monster gladly retaliating. During the struggle, Tōtetsu was able to seriously injure Riku as the latter risked his life to protect Towa from the former's attacks. Eventually however, Riku was able to slay Tōtetsu when he was distracted by the arrival of the other half-demon princesses. Before Tōtetsu succumbs to his wounds, Riku has one final discussion with him noting how while he may kill only those he loves, he despises him so much that he will make an exception in his case. This incident most likely made Tōtetsu the peril Riku hated the most.


 * Homura

Due to him being a servant of Zero, Riku was aware that Homura was the one responsible for the forest fire that separated Towa and Setsuna as children. When Riku discovered a weakened Tamano in the midst of a blizzard after she escaped from Homura's estate, Riku decided to save her in order to put a new plan into action. He decided to use Homura as means of figuring out how to unlock Towa's true powers, attempting to see if they would be unlocked with her anger upon realizing his role in her and her sister's separation. Wanting to observe the battle himself, Riku journeyed with Tamano to confront Homura and to see if Towa's powers had been unlocked. Upon arriving, Riku intentionally infuriated Homura by appearing to be close to Tamano, which caused the deranged mountain god to light himself ablaze in his fury. It was then that Riku silently revealed his disdain for the mountain god, mocking him for falling in love with a human and taking pleasure in seeing him burned alive.

It was from this battle that Riku orchestrated, that he was able to deduce that Towa's true powers could only be unlocked if her sister Setsuna was either in danger or killed. Riku would later regret this however, as he realized this put Setsuna in danger, thus putting Towa at risk of despair and emotional suffering.

Trivia

 * Riku claims Kirinmaru discarded him and that Zero took him in; hence why his loyalty changed. The most likely scenario is that Kirinmaru was displeased Riku couldn't make it in time to help heal the Great Dog Demon so Kirinmaru could have his final battle with him; though its possible Riku misunderstood his master's frustration, given Riku can't understand complex emotions.
 * In Episode 21, Riku is called a puppet repeatedly. This implies he is a unique Kugutsu with a will of his own. When Setsuna stated that his scent was similar to Kirinmaru, it may also be possible that he is an Incarnation like Naraku's. In Episode 27, the latter theory was confirmed when it was revealed that he was born from Kirinmaru's horn.
 * This makes Riku's relationship with Towa very similar to the one that Kagura had with Towa's father Sesshōmaru.
 * Both are demons born from the flesh of their respective series main antagonist (Kagura from Naraku and Riku from Kirinmaru) who initially served as antagonists but later became occasional yet untrusted allies of the main protoganists against their respective creators. Also, like how Kagura developed romantic feelings for Sesshōmaru, Riku developed romantic feelings for his (Sesshōmaru's) daughter Towa.
 * Riku possesses a strong fondness for modern foods and beverages, remarking how they are the most delicious things he has ever had.
 * This ties into Riku's verbal habit of telling others they are either being tasteless or have great taste. Suggesting Riku has a fondness for aesthetics.
 * Riku seems to have had contact with Europeans or at the very least knows about European culture. This can be seen from his reference to the concept of the  and that his sword is visibly European, likely Spanish, in origin. Being a pirate, he may have learned of and acquired such things from raiding European ships, which did operate in Japanese waters during the Warring States Era.
 * Riku's attempt to protect Setsuna for Towa's sake is similar to how Miroku sought to protect Kohaku for the sake of his wife Sango. Both sought to protect the younger sibling of those they loved in order to save them from sadness and emotional anguish.
 * What Riku considers as "love" seems to actually be acknowledgement of a worthy opponent; something his former master Kirinmaru also has, a desire to only fight and kill those worth his effort.
 * Riku is the first incarnation in the franchise to have not been born from Naraku's flesh, instead having been born from Kirinmaru's horn.
 * Riku is the first pure-blooded demon seen to have fallen in love with a half-demon.