Suddenly, Akatsuki Kuu is called to another world with three of his classmates, who are not all that close to each other. It seems that the three classmates were the hero and his followers. However, Kuu seems to have the protection and title of an evil god, so he becomes a sinner. Meanwhile, he regains the memory of his childhood friend Yuna, who he had forgotten about for some reason! Will he be able to meet his childhood friend in the land where he was called and made a sinner? An adventure story about a boy who does his best for his childhood friend.