As a descendant of shinobi, Jirou Azuma has been learning ninja techniques his entire life. But in addition to that, he also has the ability to talk to animals. One day when he rescues a strange black cat named Ragou, he learns that the world is filled with spirits called mononoke that can take the form of both people and animals. However, their meeting is cut short when they are attacked by a hostile mononoke who is after Ragou's power.