In the misty mountains of ancient Japan, the legendary warrior and spellcaster En no Ozunu succumbs to an onslaught from a demon army. But when a last-minute transmigration ritual sends him forward in time to the modern day, his consciousness ends up in the body of Yamato Katsuragi, a shy, bullied student. As the two learn to share a body, monsters continue to take the lives of innocent, unsuspecting humans. Can this unlikely duo defeat the supernatural hordes infesting their world?