The Child Who Betrayed Himejima Is the Other Disciple of the Former Thunder Hashira
Gyomei Himejima's tragic backstory showed that he used to live in a temple where he took care of nine orphan children who had nowhere to go. While they were poor, they were happy. But one night, one of the kids broke the rule of not going out at night and was approached by a demon. The child decided to sacrifice the others to save himself. What many fans didn’t notice is that the kid who betrayed them was the senior apprentice studying alongside Zenitsu Agatsuma, the other disciple under trainer and former Thunder Hashira Jigoro Kuwajima.
This was confirmed in an extra of Demon Slayer’s manga volume 17 that explained that his name is Kaigaku. The reason he went away that night was because the other children scolded him for stealing money from the temple. The manga’s extra also revealed that Himejima’s blindness impeded his ability to know Kaigaku was missing and that the children lied to him, telling him that he was just sleeping. Himejima found out about Kaigaku's betrayal by the demon himself, which explained how the Stone Hashira knew about it, since he had no other way to know what happened.
Kaigaku’s First Appearance in Demon Slayer Anime Was in a Memory of Zenitsu
Kaigaku is shown partially in a flashback of Zenitsu's training with Jigoro Kuwajima upon joining the Corps. Little has been revealed about the character so far in the anime adaptation. As members of the Demon Slayer Corps, Kaigaku and Zenitsu both had the right to inherit the Thunder Breathing style. Additionally, Kaigaku was wearing the same black kimono he had as a child, different from the yellow one with white triangles that Zenitsu got from his master.
Kaigaku seemed to hate Zenitsu and thought of him as unworthy to be taught by a former hashira, since he was always crying and was only able to master one Thunder Breathing form. However, despite Kaigaku mistreating Zenitsu and telling him to quit, the latter deeply respected him as his senior. Zenitsu didn’t flinch while Kaigaku was throwing fruit at him; he only believed he was right and thought of himself as inferior, which wrecked his self-confidence.
Gyomei Himejima’s Misunderstanding of Sayo’s Words Changed His Character
Gyomei is not only one of the strongest characters in Demon Slayer; he is also one of the kindest. He used to eat little himself so that the children could eat instead, but that didn’t matter to him because he loved the kids. The shock of being stabbed in the back by one of the children he raised was surely devastating. Even more so because, despite being injured while protecting the only remaining child, Sayo, and risking his life for her, he was blamed for the deaths of the other children due to her statement to the police.
Himejima never forgot about Sayo's words, and that damaged his trust in others. The saddest part is that nobody understood, not even Himejima himself, that the man Sayo was referring to was the demon. Himejima was convinced that she was just a confused little girl whose memories were twisted and that children are cruel and selfish, but in reality, Sayo just couldn't express herself well due to the shock. This was proved in a Demon Slayer’s manga extra that explained Sayo’s point of view, revealing she felt bad about what happened to Himejima and wanted to apologize to him.
Himejima's Past Gives More Emotional Depth to His Character
Himejima started thinking that the weak lie and blame others, and he believed that what happened to him was caused by the children's selfishness. He thought his suffering would have been lessened if Sayo had thanked him, but in fact, he just regrets being unable to save the other kids. This has molded his character to become someone driven by the desire to kill the demons, not protect the weak, because he suspects them, just like he did with Tanjiro.
Himejima's past gives more emotional depth to his character and the reason for his strength, which was born from the trauma of a kid betraying him, causing him to lose everything he valued. The fact that the same kid is connected to a main character such as Zenitsu highlights Gotouge Koyoharu's masterful writing skills, being able to create memorable and complex characters in Demon Slayer like Gyomei Himejima.
