Kohaku

is Sango's younger brother. He is also a yōkai taijiya, like his older sister and their late father, from the yōkai taijiya village. He was manipulated by Naraku through most of the time during the Shikon Jewel's return to the Feudal Era, and he was only kept alive by the Jewel shard in the back of his neck. Many years following Naraku's death and the Shikon Jewel's disappearance, he had become the leader of the newly reestablished demon slayers in Kaede's village.

History
When he is still an infant, his mother had died and his preteen elder sister took care of him along with their father.

During the story
Kohaku was killed by a demon named Naraku who was posing to be a castle's lord during one of the yōkai taijiya's missions and was made to kill every yōkai taijiya that was there, including his father. He is later revived by Naraku as a human puppet and had a Shikon Jewel shard embedded in his back to keep him alive and under the control of Naraku without memory of what he had done. Kohaku, at first before being slain, was inexperienced with his weapon, a kusarigama (a demon bone sickle on a chain). He then becomes a rather advanced wielder with the power of the Shikon Jewel shard.

He encountered his sister a few times not long after being under Naraku's control and at first he was unable to recognize her at all, although her face does seem familiar to him. Early on, Kohaku was ordered by Naraku to kill Kagome, but he was prevented from doing so.

Kohaku is later used as a guard to keep an eye on Rin when Naraku kidnaps her; he was to kill her or be killed by Sesshōmaru, only to fail at that.

He later served as Naraku's messenger, along with Kanna for the Shichinintai. He encountered Sango again during this time, and protected her by leading her outside Mount Hakurei without revealing his identity. He is later charged with keeping the Infant safe, along with Kanna, by staying in a human castle. When the castle is attacked by Princess Abi, Kohaku fights against Naraku's order to kill everyone and take back the Infant, crying as it's not what he wants. The time he spent in the castle, along with killing comrades awoke his sleeping memories; he nearly fell to his death from Kagura's feather before she caught him.

Deciding to redeem himself by killing Naraku, Kohaku pretended to still be under his control. This was put to the test when Hakudōshi released a swarm of demon rats, and he was left to keep the shrine they came from open. Luckily, Kikyō destroyed the shrine, allowing him to continue his ruse. Later ordered to kill Parasitic Chrysalis, Kohaku revealed he regained his memory to Kagura, gaining a shard of demonic energy to track the Fuyōheki with; Naraku's heart, the Infant had it in his possession, and if the Infant was slain, Naraku would die with it. Kohaku was then tasked with slaying demons, meeting a father and son who helped bind a wound he received while tracking a parasitic demon; it possessed the boy, who Kohaku chased after to free him from the demon. His sister arrived and drove the demon out, forcing him to leave to continue the ruse.

He eventually ran into Kagura again, and she tried killing him for his shard; Hakudōshi and the Infant had turned on Naraku and needed shards to gain power for their plan to replace him. When his determination showed Kagura the truth about their situations, she sent him away on a feather for his own safety. Sango followed, but a confrontation with Mōryōmaru forced him to reveal the truth to her. Kohaku then sought to find redemption for himself by traveling with Kikyō, and remains by her side until she tells him he must leave her to keep his shard pure. Saved from Byakuya by the timely arrival of Sesshōmaru, Kohaku forms a friendship with Rin and helps to protect her. In Chapter 529, Kohaku's Jewel shard was removed but surprisingly, he did not die or wither away. This was due to Kikyō's light releasing the Jewel shard and remaining in Kohaku's body, as explained by Kagome.

Despite not serving a combat role in the final battle with Naraku, Kohaku helps guard Rin after her rescue and gives Miroku his mask to protect him from the miasma.

Later life
During the three-year epilogue, a thirteen/fourteen-year-old Kohaku is revealed to be traveling around with Kirara, slaying Yōkai for those in need. Tōtōsai gives him a new-and-improved weapon, although he says it's heavier than his old one; Kohaku is thankful regardless. The old swordsmith then asks Kohaku if he still visits his elder sister Sango and "her brood" from time to time. With a smile, Kohaku laughs, saying "Nope, it's too crowded."

Hanyō no Yashahime
Nearly six months later, Kohaku found the skeleton bodies of two bandits and their horses, and is surprised to see Sesshōmaru who reveals the cause being a demon called Root Head. Kohaku helped Miroku fight off some of the root head's body then quickly headed to the house where his sister, nieces, nephew and Rin were. With Sesshōmaru guarding them on top of the house, Kohaku is asked by his sister to babysit her six month old son while she goes to fight.

Eighteen years later, he is now a confident young man in his early thirties and is an apt chief of the new generation of demon-slayers in place of his deceased father. He had received extensive training from the elderly Chief of the Northern Demon-Slayers and had helped their village from an attack by a praying mantis-demon, which had resulted in his nose being scarred while protecting his preteen nephew from it. He has Sesshōmaru's youngest twin daughter as one of his strongest allies. He shows his strength in what it means to be a demon-slayer and that retreating from battle is far from a sign of weakness, which he explained to Towa during a sparring session.

Personality
Kohaku is a humble and kindhearted boy who cares for his family and is very close to his sister Sango. When Naraku controlled his mind he was forced to kill everybody including his own father, leaving him in a state of shock. Naraku then used the guilt-ridden Kohaku as a pawn and puppet for his dirty work. Though Kohaku was a gentle boy, he was easily manipulated by Naraku to commit terrible acts because of his weak heart. He desired to forget the memories of killing his father and companions and allowed Naraku to erase them so his mind would be more at ease. After several encounters with Sango and her comrades as Naraku's pawn, however, he begins to remember his sister and his life as a demon slayer. The memories bring back his extreme guilt and sorrow, thus, he decides to kill Naraku and redeem himself. Kohaku is also very self-sacrificing about his own life compared to others, such as giving his own life to save Kagome, who had been taken hostage by Naraku. Kohaku's greatest desire is to face his father and comrades in the afterlife with an apology and be forgiven.

As an adult, Kohaku becomes more confident in becoming chief. He is also capable of training Nanasuke and Rokuta into becoming demon slayers, including his own nephew Hisui and half dog-demon Setsuna as well.

Physical description
Kohaku is a preadolescent boy with spiky dark brown hair that he styled into a Japanese topknot by a yellow hair tie, brown eyes, and freckles along the brim of his nose.

Almost two decades later, Kohaku is much taller and his freckles have faded. He now has a small scar running across his nose.

Outfit
Kohaku wears a sleeveless lavender kosode with dark violet patches, a matching sash around his waist, and white wraps around his wrists and shins.

His yōkai taijiya outfits consists of a black skin-tight jump suit with light green outlines, yellow armor plates made of yōkai parts that include black tekkou arm guards and yellow sune-ate shin guards, and a light green sash around his waist to carry his wakizashi (medium-length sword). His gas mask is worn over her lower face, while his various poisons and grappling chains are stored under his armor plates.

As an adult, he still wears a lavender kosode, but the sleeves are long, and he wears a brown vest over it. He wears black baggy pants, white socks, and getas. His yōkai taijiya is identical to the one he wore when he was younger, and he wears a short black and red shoulder cape over it, tied with a yellow string.

Powers & Abilities

 * Peak Physical Condition: Like the rest of his demon slayer kin, Kohaku has undergone special training designed to strengthen both his body and fortitude to their upper limits. While not quite as strong or as sturdy as his elder sister, he compensated for these flaws with his superior reflexes and agility, which had come to be the constituent for his normal fighting style; which was centered on both evasion and efficient attacks from safe range.
 * Peak Human Agility: With a physique built for celerity, Kohaku had shown on multiple occasions to be nimble and precise in movement; able to transition his body with amazing configuration and control. Kohaku’s coordination and balance had allowed him to perform acrobatic and reflexive actions like a graceful bird, and easily traverse most barriers and terrains with maneuverability. He is even more agile than his sister, contrast to her superior strength.
 * Peak Human Speed and Reflexes: Kohaku is as swift as he is graceful, able to operate and transition at speeds that has allowed him to outmaneuver even demons. Inuyasha himself has had slight trouble trying to keep Kohaku under wraps. In tandem, Kohaku has extraordinary reflexes and reaction time; able to dodge attacks from swift demons and escape confined situations.
 * Peak Human Endurance: Although inferior to his sister in that regard, nonetheless; Kohaku’s physical fortitude and endurance had been nothing short of spectacular. He had built the necessary stamina to be able to fight through grievous wounds, and survive intense battles with powerful demons with only minimal injuries. He has great survivability, and impressive robustness.
 * Peak Human Stamina: As a trained demon slayer, Kohaku possess excellent steadfastness and vitality. This trait was further magnified through the jewel shard that was formerly planted on his back; allowing Kohaku to tirelessly carry out Naraku’s assigned tasks and missions for days without proper rest or sustenance.
 * Honed Senses: Like all demon slayers, Kohaku was trained to polish both his instincts and senses to maintain heavy alertness in the midst of active combat. He has an eye for detail, and is quick to discern the presence of traveling assailants in his vicinity. Like his sister, he can also sense demonic auras, although not on the level of spiritual ascetics.
 * Expert Combatant: Protocol to the cultural tradition of the demon slayer clan, Kohaku was subjected to an intensive training regime from youth to become a skilled warrior; hindered only by his cowardice and inexperience. Albeit, after becoming enthralled to Naraku’s will; Kohaku’s gentle cowardice was erased, and his training complete; molding him into a formidable combatant. As a demon slayer Kohaku was adept in both armed and hand-to-hand combat, but where his skills truly showed depth was his favored use of the Kusarigama; a weapon of chain and sickle. Having developed the necessary manual dexterity and muscular coordination to use this weapon to its fullest effect, Kohaku is able to utilize the Kusarigama with lethal precision; able to attack enemies from a distance swiftly, and ensnare items with the attached chains without hurting anybody. His skills allows him to contend with Sango and maintain footing with the group, though they often hold back.
 * Master Strategist: Personified by his sense of caution and rational logic, Kohaku has presented himself consistently throughout the series as a prudent tactician; one who carefully plans out his actions before executing them. Rather than rush blindly into action, Kohaku often picks his battles methodically, and always prioritized escape strategies should a confrontation or mission go sideways so he can fight another day. Perhaps Kohaku’s most impressive feat of tactical wit was his remodeling of the demon slayer clan. Through nothing more than his administrative genius, Kohaku was able to transform the demon slayer clan from a nearly extinct, scattered warrior corp to its former glory; creating a new generation of demon slayers trained, and coordinated under his sole jurisdiction as their chief and commander.
 * Stealth: Kohaku had exhibited throughout the series to be an ingenious stealth artist; both graceful and unnoticeable. Kohaku’s skills in general concealment, intelligence gathering and covert surveillance had served him well throughout his crusades as Naraku’s puppet. He was so skilled as a stealth artist, he had proven capable of even rendering himself imperceptible to the keen senses of demons and was mistakened for a ninja by Bankotsu; who are renowned for their expertise over espionage. This skill had also made Kohaku the model messenger by Naraku; as his own stealth capabilities allowed for the exchange of intelligence without attracting attention.

Weapons

 * Kusarigama: Kohaku's weapon of choice is a kusarigama (a large sickle made of the bones of demons, attached to a long weight-tipped chain) which he is equally adept with at either distance or close quarters.
 * Filter Mask: Kohaku and other slayers carries a metal gas mask to prevent them from breathing in the poisonous fumes of demons.
 * Wakizashi: A demon-bone short sword, virtually identical to Sango's.

Family
He is very close to his sister; though he was brainwashed by Naraku who resurrected him from death. Kohaku meets Sango and realized her as his older sister, though he hid himself from her. Once he regains his memory, Kohaku is determined to kill Naraku secretly without letting Sango know. He feels great guilt for causing Sango much emotional pain and believes he is unworthy of life. By The Final Act, he begins to feel the burning desire to live once more and redeem himself.
 * Sango

Miroku, like Inuyasha, has desperately tried to save Kohaku several times during their meetings, even risking his own life in the process. Because he is in love with Sango, Miroku is aware what Kohaku's death would do to her and thus does everything in his power to protect his life. Kohaku later acknowledged the monk's bravery during his possession by Magatsuhi as well as his sister's love for Miroku. After Naraku is destroyed, Kohaku asks Miroku to take care of his sister for him in his absence, clearly showing he trusts the monk.
 * Miroku

Kohaku acts as a mentor to his nephew and trains him in the ways of exterminating yōkai. In turn, Hisui deeply respects his uncle and was inspired to become a yōkai taijiya by his actions.
 * Hisui

Allies
Kohaku is close to Kirara. After he regained his memories, Kohaku would spend time with Kirara. He seems to have trusts and close relationship with her, and cares for her. Kirara also feels the same, trying to save him through dangers.
 * Kirara

His first meeting with Kikyō as an enemy, Kohaku was unsure of Kikyō until he fled from Naraku and refused staying with Inuyasha's group. He came across Kikyō and begged her to use his life to destroy Naraku, thus, redeeming him of his guilt and sins. He was not phased by her warnings her plan would lead to his death, he even accepted it gladly. During their journey together, Kohaku begins to have respect and concern for Kikyō, even worrying when she puts herself in danger. Kohaku mentions his main purpose for staying with Kikyō to Sango as, Kikyō's presence calms his spirit and he feels as if sins are cleansed and redeemed around her. When Kikyō dies, Kohaku is guilt-ridden that he could not protect her and is resolved to carry out her mission to destroy Naraku with his shard.
 * Kikyō

Setsuna is a yōkai taijiya under his command. Kohaku also takes on a mentorship role to her older twin sister Towa, and identified a personality trait of hers: that she never runs, even when it would be advantageous for her to do so. Although he initially sees this as a weakness, he comes to see it as a strength by the end of the second season.
 * Towa Higurashi and Setsuna

Traveling companions
After she was abducted by Kagura, Rin met Kohaku in a shrine. They soon befriended each other. In fact, Rin lost her entire family who were slaughtered by thieves and Kohaku struggled to recover his memories when Naraku controlled him. At first their relationship started off rather horribly when Naraku ordered Kohaku to kill Rin in front of Inuyasha, Kagome and Sesshōmaru, but he refused to. They encounter each other a second time in a cave on Mount Hakurei. Kohaku protected Rin from the emerging demons, but also urged her to escape before she was killed. Later, he joined Sesshōmaru and Jaken after Kagura and Kikyō's death. In the later portion of The Final Act, Kōhaku becomes protective of Rin (as seen in Episodes 14 and 23), keeping their friendship alive.
 * Rin

Kohaku joins his retinue since Sesshōmaru saved his life from Byakuya after Kikyō's death and stays as part of his group for a considerable length of time throughout The Final Act. Kohaku is respectful and admiring, though wary of Sesshōmaru and spends much of his time guarding Rin when Sesshōmaru cannot. Kohaku is not afraid to beg Sesshōmaru to spare others' lives, an example being when his sister Sango nearly killed Rin trying to kill Naraku. Kohaku is the first to offer an excuse for her and desperately tries to convince Sesshōmaru not to kill Sango in anger. This shows that he very much cares for and would do anything to protect his sister, much like she did for him when he was young, and is in essence a role reversal (i.e. Sango settling down as a housewife and her brother becoming the dominant protector). Despite his admiration for Sesshōmaru, Kohaku finds his actions enigmatic at times, and is unable to determine what his true motives are.
 * Sesshōmaru

Years later after reestablishing the yōkai taijiya, Kohaku would take in and train Sesshōmaru's younger daughter as one of them. While encountering the Green Ogre Bunch, Kohaku sees the blast Bakusaiga unleashes and recognises that it belongs to Sesshōmaru's as he reunited with him. After he let Setsuna go to the Sacred Tree of Ages, he and Sesshōmaru joined forces to fight the ogres.

While they are traveling together, Kohaku treats Jaken with the same respect that he does with Sesshōmaru.
 * Jaken

It seemed that A-Un had no trouble being led by Kohaku when he joined the group and let him ride on his back all the time.
 * A-Un

Enemies
Though he willingly obeyed Naraku for much of the series, Kohaku always despised him for manipulating him and causing him to kill his father and comrades and wound not only Sango but countless others. Over the course of time, Kohaku's memories return and he becomes determined to kill Naraku and avenge his loved ones killed by Naraku and also to redeem himself for being used as a killer. Kohaku betrays Naraku and escapes with Kagura's help and from that point Naraku hunts Kohaku for his jewel shard. Once Kikyō uses Kohaku's shard as part of her plan to destroy Naraku, Kohaku becomes a major threat to his great enemy and Naraku is forced to plan carefully when dealing with him.
 * Naraku

Others
Inuyasha has tried to protect Kohaku from death several times including a time with Sango and with Sesshōmaru. Inuyasha is determined to keep Kohaku alive for two reasons: he does not want Naraku to get what he wants (i.e. the Sacred Jewel shard in his back), the taking of which would lead Kohaku's death and also because he knows that Sango will be grief-stricken if her brother dies. Kohaku comes to respect Inuyasha greatly.
 * Inuyasha

Kohaku gets along with Kagome very much, as Kagome risks her life to save Kohaku because she knows that Kohaku's death would be devastating for Sango, whom she cares deeply for. Kohaku says that Kagome reminds him of how Kikyō was, which meant that he always felt calm when he was around her. Kohaku also protects Kagome because she is best friends with Sango and gains respect when he sees how powerful Kagome can really be. There was a time when Kagome asked Sesshōmaru to spare Kohaku's life when he was going to kill him instead, that was when Kohaku was still under Naraku's spell.
 * Kagome Higurashi

Trivia

 * The new kusarigama that Kohaku received from Tōtōsai is extremely reminiscent of the corrupted weapon that he had when he was possessed by Magatsuhi.
 * As stated by Sesshōmaru's mother, Kohaku can't be revived by Tenseiga because his life has already been unnaturally prolonged.
 * In the early series (manga and anime), the jewel shard that kept Kohaku alive was in the middle of his back. Towards the end, it was at the top of the neck.
 * His seiyū, Akiko Yajima, voiced Inuyasha and Kagome's enemy Yura.
 * His second seiyū for Hanyō no Yashahime, Ryohei Kimura, voiced Tsubasa Jūmonji of Kyōkai no Rinne.