Kuu is Hajime's cat that serves as a "police cat" of sorts. Hajime keeps him in the guard room of Nanba Prison since he can't have pets at his apartment. The cat tends to follow Hajime around everywhere.
Kuu is a fluffy black cat with green sclera. He has a scar over his left eye, resembling Hajime's. He wears a black hat with a gold C and braiding on it. It is similar to the uniform caps worn by the prison guards.
- Kuu means "Nine"
|Main||Jyugo | Uno | Rock | Nico | Hajime Sugoroku|
|Inmates|| Tsukumo | Honey | Trois | Musashi | Liang | Upa | Qi | Fuji-san | Kusatsu | Enki Gokuu | |
Ruka Gojou | Hachiman
|Guards|| Seitarou Tanabata | Yamato Godai | Samon Gokuu | Kenshirou Yozakura | Kiji Mitsuba | Inori Hakkai | Damian | Mao Nimaijita | Nijimasu Nanairo | Tomato Ichijou | Hitoshi Sugoroku | Houzuki Sanzou | |
Daisen Rokuriki | Daisen Kokoriki | Daisen Youriki | Genrou Byakuya| Ahato
|Nanba Staff||Momoko Hyakushiki | Mitsuru Hitokoe | Shiro | Okina Otogi | Kazari Otogi | KAGU-8|
|Antagonists||Man with the Scar | Elf|
|Other||Kuu | Haku | Yamatomaru | Hanzou Hattori | Noriko Sanzou | Hihi Gokuu | Inmate 610|