Genius middle schooler Takamine Kiyomaro has an apathetic attitude towards life and is an outsider at his school. One day, Kiyomaro meets a mysterious boy called Gash Bell: Gash was found unconscious out in the woods of England by Kiyomaro's father, and has lost all his memory. The only clue to Gash's identity is the red book he was carrying when he was found, but it contains letters no one can seem to decipher. However, when Kiyomaro looks through the book, he notices that there is one word he can read, and when he does, thunder comes out of Gash's mouth. It turns out Gash is a mamono (Ã¢ÂÂmonsterÃ¢ÂÂ) boy from makai (demon world), and that he has been sent to the human world along with 99 other monster children to fight out a battle for who will be the next king of makai. All the monster children have their own books, which will enable them to use magic when they find the right humans to read them. Monster children keep coming to Gash and Kiyomaro to beat them.