Hasukawa Kazuhito got amnesia so he only remembers the last 5 years of his life. His girlfriend is Aihara Hikaru, who always gets into trouble in her work. One day he receives a letter and meets the girl who said she is Kazu girlfriend before he amnesia. Still confused, Kazuhito is to be sent to future by Makoto, a empoyee of the Culture Department. She tells Kazuhito that his real indentity is Kai, the Legendary member of Nightmare, a illegal organization under the Culture Department. Kazuhito must adapt to his new life. Tokyo was separated from Japan, and he knows nothing about the suspicious organization with young members. And who was Kai?

Yuuji Abe meets a mysterious girl at the subway station. This chance encounter with Kana and Rou, her wolf companion entangles Yuuji in a plot concocted by the Seven Heads, a group of half-demons who want to bring a type of utopia where humans and demons can live together peacefully, albeit through unscrupulous and forceful means. As the group targets Kana and her companions, Yuujo begins to discover the truth not only about Kana, but about his own ancestors, and ultimately comes to terms with his budding feelings for this mysterious girl.