In a world filled with shadows and lurking monsters, Haruto Raikou is an ordinary high school student. On his last day of school, he witnesses a terrifying scene: a group of men attempting to abduct his crush. In his brave attempt to save her, Haruto is severely beaten and left on the brink of death.

When he awakens, Haruto finds himself in a strange new world, filled with demons and monsters. He soon joins a group of hunters, determined to protect the innocent. During a dangerous mission in a cave, an unexpected disaster strikes, forcing Haruto to confront his fears.

Now, part-demon himself, Haruto must grapple with his new powers and the difficult choices ahead. Will he give in to the darkness or fight to become the hero he wants to be?