Rainbow

The year, 1955. Six delinquents nicknamed Mario, Cabbage, Soldier, Turtle, Uncovered, and Joe are taken to a prison-like reform school due to their various crimes. They are introduced to Dr. Sasaki, the school physician, who performs a painful rectal exam on each boy. Humiliated, they are led to their cell-like room, where they met a boy named Sakuragi. Mario starts a fight with Sakuragi, culminating in Sakuragi knocking out all six boys. Ishihara, the school's sadistic head guard, violently beats Sakuragi as punishment while the others watch. Later after Sakuragi regains consciousness, he accepts a stashed cigarette from Joe, then proceeds to share it with the others. Sakuragi's strong, yet benevolent actions immediately earns him the respect and admiration of the six boys.

The seven boys have become comrades and spend time working out in their cell. Joe reveals that he has a younger sister on the outside. Seeing her again is his sole motivation to endure the school. Joe later receives a visit from the orphanage administrator where his sister is staying saying his sister is about to be adopted. Afraid he will not see her again, Sakuragi and the other boys cause a distraction allowing Joe to escape through an unguarded entrance. The boys are beaten and placed in solitary confinement. Turtle recounts losing his entire family in the atomic bombing of Hiroshima and why he helped Joe escape. Joe arrives at the orphanage and attempts to escape with his sister but is caught by the police. Joe's sister 'rejects' him and sends him away (in an attempt to protect him). Distraught, Joe is returned to the school and placed in solitary.

Joe leaves solitary and Sakuragi's words are able to comfort him. Joe resolves to survive and one day reunite with his sister. Ishihara tells Uncovered that Sakuragi murdered his parents. Uncovered confronts Sakuragi in the mess hall, resulting in the two almost coming to blows. Sakuragi is taken and beaten by Ishihara who greatly hates Sakuragi for being the lone student in the school who is not afraid of him. Uncovered remembers his early childhood being poor and how his mother was sexually exploited to get food, causing him to develop a distrust in others. Ishihara discovers Uncovered with a stash of hidden cigarettes. Using Uncovered's fear of him, Ishihara schemes to implicate Sakuragi. A fire, ignited by one of Uncovered's tossed cigarettes, causes an evacuation of the cells. Uncovered is horrified when Ishihara purposely throws away the key to Cell 6, in an attempt to kill Sakuragi. Sakuragi confronts Uncovered outside and learns the other boys are trapped in the burning building and rushes back inside in an attempt to save them.