Nishiki Nishio

Nishiki is a lean young man marked by his glasses and untidy hazelnut hair. Like other ghouls in hiding, he keeps to ordinary casual clothes to pass among humans, and he wears a pair of bangles chosen by Kimi Nishino so the two would match. Around the Owl Suppression Operation he trimmed his hair into a bowl cut resembling his first year at university. After the time skip he takes on the guise of the ghoul Serpent, cloaked and hooded behind a snake-shaped mask. Unmasked in that period, he carries a fresh scar over his left eye, his hair has grown out again, and his expression has turned notably more sorrowful.

Nishiki is a hardworking prodigy of a student saddled with a prickly arrogance. His tongue is blunt and often cutting, and he insists that those younger than him treat their elders with respect. Beneath the abrasiveness lies a wary man slow to place his trust in anyone, though he proves capable of fierce loyalty and will put himself in harm's way for Kimi. As a boy he shared Kaneki's discomfort, questioning the eating of humans and his sister's outlook while loving her deeply. Her death at the hands of the CCG shattered that trust, leaving him a loner who guarded his feeding ground and first approached Kimi only to exploit her. After she accepted his ghoul nature, he came to treasure her above all and joined Anteiku so he could eat without killing. By the time skip he has become a ghoul who preys on ghouls, casual and sarcastic yet ruthless, coldly disposing of anyone he finds troublesome while carrying a quiet grief over what has become of Kaneki.

Nishiki and his older sister grew up parentless and poor in a run-down shack, and as a child he refused to eat human flesh while she worked to feed and better them. When the shopkeeper she admired sold her out to the CCG, she was killed, and Nishiki avenged her by killing the man. Living on under the name his sister left him, he enrolled at Kamii University and approached Kimi Nishino, at first only to use her.

He first crosses Kaneki's path by recommending a brand of instant coffee, then kills Kazuo Yoshida for feeding within his territory and turns on Kaneki for the same reason, only to be beaten by Touka Kirishima, who declares the ground belongs to Rize Kamishiro. When Kaneki and Hideyoshi Nagachika later visit him, he lures them out, attacks, and is about to kill Hide before Kaneki's kagune awakens and pierces him repeatedly. Left badly weakened, Nishiki is set upon by ghouls of the 14th ward and rescued by Kaneki, and after Shuu Tsukiyama abducts Kimi, the two join with Touka to defeat him, a fight won through Nishiki's stubbornness and Kaneki's willingness to be partly eaten by Touka. He then takes work at Anteiku.

Through the Aogiri and Owl Suppression arcs he stays with Anteiku, helping rescue Kaneki and tutoring Touka for her exams. After the time skip he becomes an S-rated ghoul dubbed Serpent, notorious for hunting other ghouls, and clashes with the Quinx Squad and with Haise Sasaki, recognizing his old friend Kaneki mid-battle and fleeing in sorrow. On Rushima he pursues Kanou, whose new lab assistant is Kimi, and teams with Kurona Yasuhisa against Roma Hoito before escaping the island. Afterward he joins Kaneki's newly formed Goat and settles in the 24th ward, and by the epilogue he devotes himself to supporting Kimi's research. In combat he relies on a bikaku kagune that magnifies the force of his kicks, backed by exceptional durability, strength, and agility.