Byakuya

also known by his alias was Naraku's ninth and final incarnation, meant to replace Kagura. His main purpose was to observe Inuyasha and Mōryōmaru's growing powers and report back to Naraku.

History
The time of his creation is left to speculation, but it was following the deaths of Kagura and Hakudōshi; Naraku was absent from the story for a while. This perhaps means, he was conducting trial and error in producing detachments and Byakuya is the final result.

During the story
Note: This section describes what originally happened in the manga, not The Final Act anime adaptation.

He originally appears when Inuyasha fights a poisonous demon that swallowed some of Mōryōmaru's flesh and gained power. Byakuya created illusions to distract Inuyasha and allow the demon to flee. He appeared before Inuyasha to introduce himself, right after telling the demon where he was. Byakuya watched as Inuyasha slayed the demon and was hit by a backlash of energy from Tessaiga. He warned that if another enemy was around, Inuyasha would be dead. Byakuya took his leave to report back to Naraku, commenting those his orders were to simply observe, he didn't kill Inuyasha when it would have been very easy to do so.

Byakuya next appears right after Meiōjū is resurrected by Mōryōmaru to gain a powerful armor. At that time, he met Sesshōmaru, who, just like Inuyasha, attacked him because he smelled like Naraku. When Mōryōmaru got the armor and Diamond Spears of Tessaiga, Byakuya was order to distract Sesshōmaru to allow Meiōjū to escape. Escaping death, Byakuya explained he was simply doing his job.

Followingly, Naraku promised a demon (who used to be a human sage) a Shikon shard in exchange for Inuyasha's death; this happened during a new moon. Byakuya captured the fleeing head of the demon in a web, taking back the shard in it, promising to gift it to the body that grew a new head if it succeeded. The demon was slain by Inuyasha, who gained the ability to purify the yōketsu sucked in by Dragon-scaled Tessaiga.

On Naraku's orders, he had a badger demon attack the wolf demon tribe and gave a young pup named Kai a Shikon shard to lure Kōga to him in exchange for the life of his younger brother Shinta. He succeeded in luring in his prey, but was forced to flee once more when Inuyasha's group arrived to help. Mōryōmaru was caught in the middle of the skirmish and took the shard from Kai. He left Shinta trapped by a moth demon of his creation, allowing Mōryōmaru to devour it; he fled soon afterwards as Inuyasha's group saved the pup.

In the anime: Byakuya went after Kōga's shards through the same methods in the manga, at the same time Inuyasha obtained the Dragon-scaled Tessaiga. He also watched Mōryōmaru eat Ginka and Kinka, while creating a distraction to keep Sesshōmaru from sucking Mōryōmaru into Hell with the Meidō Zangetsuha.

Trying to complete the jewel
When Kikyō was successfully captured in Naraku's spider webs, allowing him to corrupt her, Byakuya was tasked with finding Kohaku and taking his shard. Meeting for the first time, Byakuya greeted the boy and attempted to kill him. However, he failed when Sesshōmaru's group rescued him.

Naraku later sent him to give Kanna an order, which was for her to release Mirror demon form of her mirror to attack Inuyasha and steal Tessaiga's powers. Byakuya watched in confusion as Kanna took on the wounds her Mirror Demon would have, realizing it was a walking voodoo doll. He laughed that his enemies should be trying to kill Kanna instead of trying to reason with her, temporarily thinking Kanna became angered by this. He then came to the conclusion Kanna had no heart, even though he was wrong. After Naraku made Kanna explode along with the Mirror Demon, Byakuya noted Naraku has a cruel streak in him, even towards his loyal incarnations.

He later came to the site of the battle between Shishinki and Sesshōmaru, demanding that the rock children tell him everything that happened there. He was later ordered by Naraku to run interference if Sesshōmaru and Inuyasha's group tried running to help Kohaku, when Naraku trying to take his shard to complete the jewel. He summoned vines filled with miasma to block them, but Miroku sucked in the poison. When Inuyasha tried killing him, Byakuya quickly got out of the way, substituting himself with another doppelgänger.

When Naraku was recovering from the damage caused by the repaired-and-improved Hiraikotsu, Byakuya was given a remaining shard of the Mirror Demon. Much to Byakuya's confusion, he was ordered to give it to Sesshōmaru, in Naraku's plan to exploit his hatred of Inuyasha to destroy him. He transported the brothers to another dimension to allow a peaceful battle without interruption from their respective groups, while he watched with his eye demon. A recovering Naraku placed a tentacles in Byakuya's eye socket, allowing him to see what the eye demon saw; this only disgusted Byakuya.

Returning to where Naraku was hiding, Byakuya watched as his master conversed with the Shikon no Tama; a purple light swirled out of the jewel and pierced Naraku. A new being emerged from Naraku's body and took off. Byakuya assumed that he now had a younger brother, but Naraku told him it was the evil will of the demons trapped in the jewel, Magatsuhi; releasing it from the jewel was the best plan to corrupt and obtain Kohaku's shard. When Magatsuhi failed to return, Byakuya learns from Naraku that the demon had failed in the attempt to take Kohaku's shard and lost the temporary body given to it. However, he also heard that the evil spirit had another plan in the works.

Byakuya later uses a piece of Magatsuhi's flesh to create a more convincing illusion of him to lure Sesshōmaru away from Kaede's village, placing it in his gourd. Upon meeting, the return of Sesshōmaru's left arm confused Byakuya. When his ruse was eventually discovered, Byakuya hoped to continue impeding Sesshōmaru's return to Kaede's village by summoning 1000 demons. However, much to his amazement and disbelief, Byakuya watched as all the demons that he gathered were reduced to nothing more than pieces of corpses in less than a minute.

The final battle
With the Shikon Jewel completed, Byakuya questioned what Naraku would do with it, only to learn he had no real plans past killing Inuyasha's group and Sesshōmaru. Byakuya noticed that Naraku had defiled the jewel to the point where there was no more room for Magatsuhi to return. Naraku transformed into a giant spider, creating a powerful storm that lured lesser demons to him. Greeting Inuyasha's group as they arrived with Sesshōmaru, Byakuya watched in amazement as they all went inside Naraku. This only left Byakuya laughing at his enemies' stupidity once again; they should just forsake Rin and safely destroy Naraku from the outside.

He watches as Naraku curls into a ball, turning into an ominous replica of the Shikon Jewel. Byakuya later teleports inside, where helps spread the light from the Shikon jewel around, to lure Miroku and Sango into traps. These traps involved Byakuya creating an illusion of Naraku for each of them, Sango was to be tricked into destroying Rin while Miroku would be tricked into opening his Kazaana. Neither illusion worked.

After taking the power of one slash of Inuyasha's Meidō Zangetsuha, he thinks to himself that the end is near, informing us that he knew he was going to die like the other incarnations. When Shippō sees him take the Meidō Zangetsuha's demonic energy, he is aware, but he doesn't capture Shippō; in fact, he informs him that he has a chance to get out of Naraku's body alive. Later, Byakuya slashes Kagome with the blade that contained Meidō Zangetsuha's demonic energy. However, before he gets a chance at a second strike, Inuyasha attacks him with his Meidō Zangetsuha and Byakuya is absorbed into it, but not before he states to Inuyasha that he has fulfilled his purpose, and that he has no regrets.

When Naraku's soul disappeared forever from the material world, a Meidō appears behind Kagome, due to Byakuya's Meidō blade.

Personality
"Naraku's got a cruel streak in him. I'd best keep an eye out." Byakuya appears playful and polite, introducing himself to others and expecting the same courtesy; he loathes how Sesshōmaru tried killing him without even an introduction. Logical and observant, Byakuya doesn't want to arouse the anger of someone he knows can kill him, like Sesshōmaru. He is willing to kill others Naraku hates, but won't go against his orders. He is also willing to help others, even his enemies, such as when he told Shippō how to escape Naraku's body. He'll often voice his opinions, such as when his opponents do something stupid; Inuyasha could have killed Naraku with the Meidō Zangetsuha, but chose to go inside him to rescue Rin.

When he mocked Inuyasha for not trying to kill Kanna directly to defeat the Mirror demon, Byakuya feared that he angered his eldest sister. However, he quickly abandoned the idea when she didn't so much as give a glare at him, wrongly concluding she was truly emotionless. He fears for his own life, taking note as to how Naraku made Kanna explode in an attempt to kill Inuyasha's group. Byakuya has been seen to accept compromises, given he ordered Kai to bring him Kōga's shards, but decided Kōga himself was just as good when he followed after Kai. It would seem Byakuya likes to twist his words around so it doesn't seem like he's lying; he let Shinta go free from his possession, only for a moth demon to carry him away and put him in danger of Mōryōmaru absorbing him.

Though he often appears calm, even amiable at times, he is capable of being caught off guard, such as when Sesshomaru used Bakusaiga's yoki wave to annihilate the 1,000 demons that Byakuya summoned, with his reaction being obviously unnerved and cowed by the dog demon's powerful new sword.

Physical description
Similar to a moth yōkai, Byakuya has pale skin with purple eyes. He has long black hair, which is tied in a ponytail with bangs, and his lips appear to be painted red. His outfit consists of a light blue haori with red patterns on it. Byakuya wears brown hakama with them. He also wears a dark blue vest with yellow markings on it. He wears socks with his sandals. Byakuya keeps his bladeless sword tied to his back along with his gourd.

Powers & Abilities

 * Illusions: By blowing dew off a blade of grass, Byakuya is able to create a multiplication illusion. By surrounding someone with origami cranes, Byakuya can temporarily prevent his victim from being able to see beyond the ring of cranes; he used this to allow Mōryōmaru to flee in The Great Holy Spirit's Test. He can also create multiple, similar, illusions (specifically of Naraku) in different places; however, Byakuya comments that it's a lot of hard work. Byakuya has also created an illusion of Magatsuhi, using a piece of flesh with its scent to make the illusion more believable.
 * Teleportation: Whenever he's attacked, Byakuya substitutes himself with a doppelgänger, which turns into a flower in a blue flame when attacked; he tends to hide somewhere nearby, or flee. He can also teleport without a substitute, appearing out of a spiral of red energy or vanish in a wave of air. Byakuya holds out a flower before teleporting away, perhaps meaning they're a medium for this ability.
 * Barrier: Like Naraku, the Infant and Hakudōshi, Byakuya has the ability to create and fly in a barrier for his own safety if flying on his origami crane is too dangerous at the time. He only used this once in the manga, where he was ordered to distract Sesshōmaru so Meiōjū could be absorbed by Mōryōmaru.
 * Origami Control: His most commonly used ability, Byakuya uses it to create a paper crane to fly on after enlarging it, similar to Kagura's feather. He can also manipulate cut-outs of people for covert observation, and can possess others by simply attaching his paper to them. Byakuya can also remotely control smaller paper cranes to distract enemies. He also possess reflective sheets, which can send light anywhere he pleases.
 * Detachable Eye: Byakuya can detach his right eye at will, turning it into a flying eye demon, used to spy on foes; it's resistant to the pull of a Meidō, being able to avoid being sucked into the Underworld. He can send it to other dimensions as well; this allowed him to watch Inuyasha and Sesshōmaru's fight. Naraku can see what Byakuya does by touching his eye socket, something Byakuya finds "disgusting"; in a way, this replaces Kanna's mirror.
 * Command over Lesser Demons: Byakuya has been seen giving orders to weaker demons. He ordered a blood-thirsty demon to attack the wolf demon tribes to force them to take Kōga's shards. Byakuya can also communicate with the Rock Children, who informed him of the battle Shishinki fought against Sesshōmaru. He also gathered 1000 demons to impede Sesshōmaru's return to Kaede's village to find Magatsuhi only to see Bakusaiga destroy them almost immediately.
 * Nature Control: Though only seen once, Byakuya has the ability to manipulate vines and make them burst from the ground where-ever he chooses. If the vines are cut, miasma will pour out of them; the potency of this miasma is unknown given no one breathed it in and a potion prevented Miroku from feeling pain from sucking it.
 * Flight: Even though he can fly on his origami cranes and in a personal barrier, Byakuya has been seen to fly on his own without any aid.
 * Technique Absorption: Byakuya possesses a blade-less sword that can absorb demonic energy. It was used to sample the Meidō Zangetsuha. The purpose of this attack is still unknown, as the Meidō opened up behind Kagome some time after Naraku was defeated. Byakuya has stated that he can only do this once.
 * Link to Naraku: Like Hakudōshi before him, Byakuya is linked to his creator; however, his connection is a lot more serious. During the final battle, Kagome shot off Naraku's left arm and Byakuya lost his at the same time. When Bakusaiga was wreaking havoc on Naraku's body, Byakuya's face started to crack. Upon being hit by a Meidō, Byakuya commented he would die when Naraku did.

Weapons

 * Magic Gourd: Byakuya has used it for three different purposes. First:, Produce poisonous snakes, which he used to paralyze Kohaku and defile his shard. Second: Splash water from it to create a moon around his targets to send them to another dimension. Third: Storing a piece of Magatsuhi's flesh for its scent, to trick Sesshōmaru.

Trivia

 * As Kagura, Hakudōshi, the Infant, and Kohaku betrayed Naraku at the same time, Byakuya basically replaces all of them; this perhaps is the reason he is so powerful.
 * His outfit bears similarity to Naraku's before fleeing to Mount Hakurei.
 * Like Kanna, he does exactly what he is ordered to do, even if it goes against his own desires, although he does voice his opinion from time to time.
 * His title "" refers to his ability to weave illusions, which are dreams experienced while awake.
 * How he boards his origami crane is similar to Kagura; he holds a miniature version of it before being surrounded by a tornado, which subsides to show him flying away on the enlarged version of the crane.
 * There is strong evidence that suggests that Byakuya might be a moth yōkai. Firstly, Byakuya has many of the same powers as other moth yōkai, such as the creation of illusions, insect control, and nature manipulation. He also bears a close resemblance to other moth demons, such as Gatenmaru and Garamaru, particularly his long hair and colored lips. If this were true, it would be Naraku's first and only incarnation that was a member of a particular subspecies of yōkai; all of his other incarnations (with the slight exception of Goshinki, who was nevertheless just an oni) were standard humanoid yōkai and not aligned with any particular animal-derivation; ironic, considering that Naraku is a spider hanyō.
 * With the possible exception of Naraku (whose physical body is destroyed by Inuyasha with Meidō Zangetsuha, though it is debatable whether this can be counted as his true death, given the form he is in when he reappears), Byakuya is the last recurring character in the series to be killed by Inuyasha.
 * His seiyū also voiced Toma from Rumiko Takahashi's previous work  in the movie Nihao, My Concubine.