OKOI

The Kouga Ninja Scrolls (Japanese: 甲賀忍法帖, Hepburn: Kōga Ninpōchō) is a historical fantasy novel about ninja written in 1958–1959 by the Japanese author Futaro Yamada. It is the first installment in Yamada's Ninja Scrolls series, which he wrote until his death in 2001. The book was translated into English by Geoff Sant, and published by Del Rey in December 2006.