Saiko Yonebayashi

Saiko is strikingly short for her age and carries more weight than the typical CCG agent, with noticeably full legs. Her pale blue hair falls into two thick pigtails beneath ragged, uneven bangs that hint at how little effort she spends on grooming. One eye is a bright baby blue while the other burns red, the left one bearing the single kakugan that marks her as a Quinx. Her features look distinctly youthful, and after the six-month gap that follows the Tsukiyama operation she wears her hair noticeably shorter.

At first Saiko is defined by sheer indolence. She has no appetite for work and would rather coast through an easy, cheerful existence buried in video games and mountains of junk food. A childish streak shows in her habit of speaking about herself in the third person, and though she is self-conscious about her weight she makes little real effort to change it. Chronic oversleeping keeps her off most assignments, a symptom of how little she ever wanted this life. Becoming an investigator was her mother's decision rather than her own, which leaves her doubting her own worth.

What she hides is genuine ability, a talent for shaping her kagune that outclasses her peers. Once the Tsukiyama operation passes, she turns a corner entirely, taking her responsibilities seriously, setting an example for the newer Quinx, and supporting Urie as his second-in-command.

Saiko grows up with an older brother after their mother abandons their father and moves the children in with her new partner. The couple's struggling bar leaves little money, so the siblings are enrolled at the Academy Junior School simply because the tuition is cheap, and Saiko spends those years goofing off and clashing with her teachers. She has no wish to become an investigator, yet her strong showing on the Quinx Aptitude Test marks her as an ideal subject, and her mother accepts a hefty payment in exchange for consenting to the surgery, forcing the change on her.

Once assigned to the Quinx Squad, her constant slacking becomes a running problem. Her teammates storm her room to confront her over neglected duties, and Urie manipulates her into promising to reform by lying that their superiors want her fired, a threat that terrifies her because failure could send her back to her abusive mother. She oversleeps through key meetings, has to be carried around while still asleep, and repeatedly dodges training and combat. During the auction raid she hangs back and hides, but when the squad corners Nutcracker she unleashes her kakugan and helps bring the ghoul down, left panting and drained in the aftermath. Hearing Sasaki's agonized screams over the intercom horrifies her, and her tearful plea for her Maman not to leave pushes Haise to keep fighting as himself rather than surrender to Centipede.

Promoted to Rank 2 not long after, she is ambushed during a later trap, where the Aogiri ghoul Shikorae pins her and gnaws at her arm until a robed stranger drives him off, a rescuer she cannot yet identify. She joins the Tsukiyama extermination, where her kagune barely dents the regenerating Noro before she collapses, and she weeps at the dying Shirazu's side. After the six-month gap she has matured into a reliable member of a rebuilt squad. Her rinkaku kagune, said to hold the greatest burst power in the group, can be reshaped at will into nets, giant fists, or lashing arms, a level of control her comrades regard as natural genius.

On Rushima she recognizes the berserk Amon as the stranger who once saved her, pinning him with her kagune and asking why he had helped her before crushing him to the ground. When Urie loses control during the Clown siege, she refuses to put him down, embracing him and confessing that she loves him long enough for Hsiao to sedate him. In the years that follow she completes her own treatment, remains with the Tokyo Security Committee, and raises the next generation of Quinx alongside Urie as the doting heart of the Chateau, later nursing her dying mother together with her brother.