Saiko Yonebayashi is a Rank 2 Ghoul Investigator, a Quinx, and the deputy squad leader of the Quinx Squad. Saiko has two thick sections of hair worn in pigtails with uneven fringed bangs, possibly as a result of her laziness. Her kakugan is located in her left eye because of her status as a Quinx, and her face appears rather youthful; Saiko is a bit heavier than the average CCG agent, with notably thick and chubby legs. She is very short, especially for her age. She has light pale blue colored hair. Her right eye is a bright baby blue color while her left eye is bright red. Six months after the Tsukiyama Family Extermination Operation, Saiko's hair is shorter. Saiko is introduced as having a lazy demeanor. She dislikes having to work and prefers having a peaceful, happy-go-lucky and carefree life by playing video games and eating junk food excessively. She can display a childish nature, such as when she sometimes talks in third-person. She also doesn't really try to lose weight but is rather embarrassed of it and humorously covers it with her finger during her introduction. She often oversleeps, which earns her the absence from most missions. Her absence can also be justified by a lack of motivation; it was her mother's decision for Saiko to become an investigator. This can also lead to Saiko being somewhat insecure about her abilities. Throughout the series, we can see that Saiko is in fact very talented in kagune manipulation. Six months after the Tsukiyama Family Extermination Operation, she has become diligent in her responsibilities as an Investigator, providing an excellent example to the new quinx, and supports Urie in his duties as the deputy squad leader of the Qs squad.