Rainbow is set in postwar Japan, where seven teenage inmates are sent to Shounan Special Reform School and forced to share the same cell. Cut off from ordinary life, they face beatings, medical abuse, and relentless humiliation in a system designed to break their will and turn them against one another.
At the center of the group is Rokurouta Sakuragi, a former boxer whose strength and steady resolve make him the boys' anchor inside the institution's violent hierarchy. Around him, the others learn that survival depends not only on toughness, but on trust; each day in the school can become a punishment, a test, or a small chance to hold onto dignity.
What begins as a struggle to endure Shounan's cruelty slowly becomes a shared fight to keep their humanity intact. The boys have different backgrounds, instincts, and fears, yet the cell forces them to confront the same reality: only by relying on one another can they resist the school's attempts to isolate and crush them. A promise to meet again after their sentences gives them a reason to keep going, even when the future beyond Shounan feels distant and uncertain. Rainbow blends prison drama and coming-of-age tragedy as its cast struggles to protect hope, loyalty, and their own lives.
