Isekai Summoner, Shinwa no Kaibutsu-tachi to Gendai de Musou Suru ~Uragirareta Moto Eiyuu wa, Aiomome na Nakama to Heiwa ni Kurashitai~

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 — leading to his execution. 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 Japan. "I don't want to worry my summoned companions anymore..."