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 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...?"