Despite living in a single parent home and having a father who is a famous singer, Miryu enjoys a relatively normal life attending school and joking with his father Jin. Then comes the day when a strange girl tackles him on his way to school. She is a succubus who has mistaken Miryu for his famous demon father and has past connections to Jin that Miryu does not understand.
Shortly after, Miryu becomes sick with a high fever as he goes through a demon growth period. Jin was not planning on involving his son with the demon world, but reluctantly asks the succubus Rantain for help. When Miryu wakes he has grown to be the height of his father and they finally tell him the truth about his demon heritage. As demons and even angels continue to show up and fights start between them, Miryu becomes confused about what this means for his relationship with his father.