In ancient times swords were made to slay monsters that were powerful, but then one day a monster appeared with abnormal powers, this monster took out most of the world’s population so people built an organization to fight against these monsters, the yurei guild. A boy named akio kurogane who was in-trusted with a sword from his father after he died from the incident with the monster who attacked his town, called the “Nisshoku blade” with this sword he tries to find the mysteries about the world.