Rainbow: Nisha Rokubou no Shichinin
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.
(Summaries provided by MyAnimeList.net)