Lairs of the Hidden Gods is a 4-book series with 4 released primary works first released in 2005 with contributions by Ken Asamatsu, Masaki Yamada, Okina Kamino, Masahiko Inoue, Motoi Murata, Osamu Makino, Yoshiki Shibata, Taku Ashibe, Rio Matsudono, Mirai Matsuo and 18 others.