A man who saved the war-torn world of Eclair from a conflict between humans, beastmen, and demons returns to his home country only to be betrayed and sent back to the modern world as a baby. Sixteen years later, he's a bullied high school student named Yuki Susaki, secretly searching for a way back. Unexpectedly, he's summoned again, this time with his classmates, five years after his first adventure. Uninterested in another war, he escapes the human kingdom and seeks out old acquaintances like the Demon King and Beast King. This is the story of a slightly apathetic former hero who somehow keeps getting entangled in troublesome situations. The novel is complete and has been adapted into a manga.