Nisio Isin
The is written by Nisio Isin and illustrated by Take. The series was published between February, 2002, and November, 2005. It was followed by a spin-off series "Ningen" series starring the Zerozaki clan. A second spin-off series titled "Saikyō" series focusing on the character Jun Aikawa was also released. All books were released in Japan by "Kodansha Novels".