In Yashahime: Princess Half-Demon, Kohaku is a grown adult and the leader of the demon slayers. However, his strength and maturity only developed through the experiences he had from overcoming his inner demons and dark past. Let’s take a look at Kohaku’s journey in the original Inuyasha as he went from Naraku’s pawn to a demon-slaying prodigy, changing his ill-fated destiny.
Kohaku is introduced in Inuyasha Episode 24, “Enter Sango, the Demon Slayer,” as a young and gifted demon slayer. Sango, Kohaku and their demon-slaying comrades must slaughter a spider demon that has been terrorizing Kagewaki’s castle. Sango takes down the demon, but she discovers that it's a trap. Kohaku gets possessed by the real spider demon and slaughters his father and comrades. Kohaku injures Sango but is shot to death by the castle guards’ arrows. Naraku resurrects Kohaku by placing a fragment of the Shikon Jewel and uses Kohaku as his underling.
Naraku erases all of Kohaku’s memories to maintain control over him, even manipulating Sango into stealing the Tessaiga in exchange for Kohaku’s life. Throughout the series, Naraku uses Kohaku to do his bidding. It causes great suffering for Sango to see her brother commit evil acts, and she wavers on whether or not she should kill him.
Naraku manipulates the siblings' relationship. In Episode 49, “Kohaku’s Lost Memory,” Kohaku suffers from amnesia and ends up reuniting with Sango. He learns a bit about his past, but their time together is cut short once Kohaku hears Naraku’s voice in his head demanding he kill Kagome. Sango decides to kill Kohaku and then herself, but fortunately, Inuyasha prevents Sango from making a horrible mistake by stating that Kohaku didn’t kill Kagome.
Kagura, Naraku’s reincarnation, reveals that Kohaku is under Naraku’s control because he wishes to forget the memory of killing his father and comrades, proving Kohaku feels guilty about his actions. Naraku may manipulate the siblings’ emotional well-being, but Sango continues to believe she can save her brother.
Sango and Kohaku’s familial bond is so strong that Naraku couldn't completely control Kohaku’s mind. Kohaku was still able to recognize Sango because Naraku couldn’t erase all of his memories. In Episode 163, “Kohaku, Sango, and Kirara: The Secret Flower Garden,” Kohaku tells Kirara that he regained his memories after he slaughtered villagers to protect the Infant, one of Naraku’s reincarnations.
This incident triggered his memories about the time he killed his father and fellow demon slayer comrades. Even though he regained his memories, Kohaku tells Kirara that he is unable to return to Sango because he doesn't have the courage to face her. No longer Naruku's puppet and taking responsibility for past mistakes, he decides to avenge his family and his name by killing Naraku.
Naraku forced Kohaku to commit many heinous crimes, from killing innocent civilians to releasing a plague of demon rats to kidnapping Rin. Yet even though Kohaku committed such actions, Sango continues to help him find salvation. In the Final Act, Sango learns that Kohaku is free from Naraku’s control, but he isn’t ready to confront her yet. To seek redemption for his sins, he travels with Kikyo until she tells him to leave so that the shard within him maintains its purity.
In the battle against Magatsuhi, Kohaku tells Sango and Inuyasha that he desires to live and he’s going to forgive himself for all the sins he committed in the past. When Naraku retrieves the Shikon Jewel shard in his neck, Kikyo’s light revives Kohaku allowing him another chance at life.
Kohaku came along way in his path to retribution. He felt guilty over the deaths of his father and comrades and has contemplated suicide to end his pain. However, he realizes that he can change his destiny by forgiving himself and taking responsibility for his actions. In Yashahime, Kohaku is the leader of the next generation of demon slayers and oversees the training of Sesshomaru’s daughter, Setsuna, and his nephew, Hisui.
Although he doesn’t have a prominent role in the series yet, his role as the head of the demon slayers shows that he’s truly redeemed himself, living a humble lifestyle and dedicating his life to protecting the innocent.
