Reima, a Summoner, was transported to another world where he defeated the Demon King and became a hero of the people. But his power, great enough to even slay the Demon King, came to be feared as a threat to humanity which resulted in him being executed. Bidding a silent farewell in his heart to the summoned beasts who fought at his side, he thought his life had ended... yet he awoke in a hospital in a parallel Japan? It's just like his original world, but now there's dungeons to be explored and monsters on the loose. Strangest of all, his summoned beasts are still with him! "I'm relieved that I get to see my summoned beasts again but it seems their love is heavier than before...?"

Akihito is a prisoner who was not taught common sense, was isolated for 10 years, committed mass murder, and was sentenced to 500 years in prison. A system called "sinner transfer students" is proposed to him, which allows him to transfer to a problematic high school and reduce his sentence by solving school troubles. He infiltrates a delinquent high school, and sometimes an all-girls high school, and solves problems with his natural cheerfulness and violence. Will Akihito ever be released and get a free life...? (Source: Piccoma, translated)