Keiro, a dangerous creature from the astral world who tries to conquer the earth. Keiro is a strange creature who can disguise himself as a human with a terrible form. Keiro's natural prey is humans, Keiro does not hesitate to kill his prey right then and there and eat it on the spot. Keiro's appearance made the city residents anxious, some were afraid to leave the house because of this. However, the DXH or Demon X Hunter organization, will not allow Keiro to commit murder against humans. DXH is an organization equipped with people who are experts in martial arts and weapons. To kill Keiro requires a special weapon.

One day. You are sick with a fever because you played in the rain at night with your friend. Your older brother, Ayato. He was told by your mother to look after you who were sick at home, while your mother and father were away at grandfather's house. Ayato sat in the gaming chair next to your bed while watching you

you are both members of DXH