July 1955. Six juveniles, including Minakami Mario, who were considered to be heinous criminals, were sent to the Shounan Special Reformatory. After being treated like insects by the instructor and undergoing a humiliating physical examination, they were placed in a room called "Block 2, Cell 6." In the midst of repeated fights and abuse, they face absurdity and live strongly under the teachings of their senior cellmate Sakuragi Rokurouta (a.k.a. "Bro").