Now there's a mysterious Mask before James Blood, and the man behind it is one that shouldn't exist. What is the mystery surrounding this mask...? So begins an action-packed crime story set in a beautiful city!

In the future, the moon is a habitable place with atmosphere and gravity and also a famous tourist attraction. There are also stories about a "long ears" creature like rabbits on the moon who can use magic. Haruka Daichi heads off to the moon during a summer holiday alone because he likes to see the long ears creature by himself. However, he get himself dragged into an ancient conflict between two ancient moon races: the "long ears" race and Jado race. Jado race wanted to conquer the universe and resurrect ancient evil powers to seize control of the Earth. Now the "long ears" race and Daichi must seek three warriors who could use magic to release Mado King to fight Jado race and to release "long ears" race's kingdom, Rabiluna, from Jado race.

Since the death of his parents, Shinpei Ajiro had lived with the Kofune family and their two daughters—Mio and Ushio. Although he then left his home island to continue his education in Tokyo, Shinpei returns after Ushio tragically drowns during the attempted rescue of a little girl. During the funeral, his best friend informs him about bruises found around Ushio's neck, casting doubt over the cause of her death. Suspecting a murder has taken place, Shinpei reevaluates recent events, but strange incidents only continue to transpire. Disappearing people and other unexplainable occurrences lead Mio to recall an old folktale referring to entities called "Shadows," which may not be entirely fantasy. Supposedly, an encounter with one's Shadow foretells the person's impending demise. Facing the dark side of Hitogashima Island, Shinpei stands against his grim fate to fulfill Ushio's final will—to protect Mio.

The series stars Hat, the descendant of a hero who fought an evil king and sealed Devildom. Hat falls into Devildom and finds he has to defeat the evil king.