Nishio Nishiki, a ghoul who originally had his feeding territory taken over by Rize Kamishiro, is a second-year student in the Pharmaceutical Department of Kamii University. He is introduced as an abrasive, sharp-tongued individual whose outward arrogance and aggression mask a deeply wounded past—his sister was killed by the Commission of Counter Ghoul, an event that shattered his ability to trust others and pushed him into a lone-wolf mentality. His motivations center on survival and, initially, a disdain for forming attachments, but a turning point occurs through his relationship with Kimi Nishino, a human he originally intended to use. After a brutal fight with Ken Kaneki leaves him critically injured, he consumes part of Kimi to recover, yet her acceptance of his true nature forces him to reconsider his isolation. This relationship becomes the foundation of his growth, leading him to join Anteiku as a waiter to secure a stable food source and avoid killing humans. His role in the story evolves from a secondary antagonist to a complex ally, and in later events he earns the nickname Serpent for his ruthless hunting of other ghouls, showing little regard for the lives of humans or ghouls alike. His interactions with Kaneki serve as a foil, highlighting themes of trust and moral ambiguity. His notable abilities stem from his Bikaku Rc type kagune, which manifests as a long, serpentine tail that he wields with precision in combat, granting him enhanced speed and strength. Over the course of the narrative, Nishiki undergoes significant development, shifting from a self-centered, distrustful ghoul to one capable of deep loyalty and emotional vulnerability, particularly toward Kimi. He remains a morally gray figure, pragmatic and resilient, whose character illustrates the struggle for identity and belonging in a world that demands both monstrous and human choices.