Seven teenagers in 1955 have to learn to live together in the same hold in the reformatory of Shio. Confined in a hall where suffering and humiliation are daily, they are waiting for a ray of hope in a dark, incarcerating world. The story follows their life together and how they move on afterwards.
Fresh out of college, Kumiko "Yankumi" Yamaguchi becomes a math teacher at Shirokin high school. Unfortunately for her, she's assigned by the school board as the homeroom teacher for class 3-D, which happens to be the class of delinquent students. When the class attempts to make a living hell out of Yankumi's career, they fail as her persistence and aggression gain her respect. However, little does anyone in the school know that Yankumi is actually heir to the Oedo Group - one of Tokyo's most powerful yakuza clans. If anyone finds out that Yankumi is a yakuza member, her career as a teacher could be in jeopardy.