Yuusha, Yamemasu

Yuusha, Yamemasu follows Leo Demonheart, the hero who stops Demon Queen Echidna's invasion of the human realm with overwhelming power. Instead of being celebrated, Leo is feared by the very people he saved, who see his strength as a danger to humanity's future and cast him out of the kingdom. With nowhere left to belong, Leo wanders the land until rumors reach him that Echidna is rebuilding her army. Hoping that demonkind might accept him where humans would not, he returns to the demon queen's castle and offers his help. Echidna rejects him outright, but Leo refuses to leave. By convincing Echidna's four generals to let him work under their supervision, he takes on the masked identity of a dark knight named Onyx and begins solving the demon army's problems one by one. As Leo quietly improves life around the castle and helps stabilize the demon realm from within, he also pursues a deeper answer: why Echidna started the war in the first place. The series blends fantasy, comedy, and political tension as a feared hero learns that the side he once fought may be the first place willing to give him a role.