Chiyo is the younger sister of the , Mari Kurihara . While Mari is cold, dominating, and ruthless, Chiyo is warm and gentle. Chiyo initially has no idea about the "Prison School" system where the male students (Kiyoshi, Gakuto, Shingo, Andre, and Joe) are imprisoned and tortured for peeping at the girls' bath.
Chiyo's story begins when she develops a massive, innocent crush on the protagonist, . chiyo kurihara prison school
: Supporting character and member of the school's Go Club. Chiyo is the younger sister of the , Mari Kurihara
: An avid fan of sumo wrestling, a hobby that serves as the initial bridge between her and Kiyoshi. Chiyo's story begins when she develops a massive,
Chiyo’s primary role in the narrative is as the love interest of Kiyoshi Fujino, the series' main protagonist. Their relationship serves as the emotional anchor for Kiyoshi throughout his incarceration in the school's prison block.