The world here is divided into another world and the present world. The present world is ruled by humans, while the other world is ruled by the spirit race like a fantasy world. At the same time, there are also ghosts, demons, elves and sealed extremely unstable races - demons - other than the spirit race. The other world and the present world should not interfere with each other, but as the years go by, there are commotions between the other world and the present world. Marriage between the two worlds is the biggest taboo. One of them will be cursed and will never recover. At this time, it was rumored that the son born between humans and spirits miraculously survived. He was known as the Demon Spirit Master. He traveled around to maintain peace between the two lives and seek ways to lift the taboo.