The Kouga Ninja Scrolls (甲賀忍法帖, Kōga Ninpōchō) is a novel written in 1958-1959 by the Japanese author Futaro Yamada. The novel has been translated into English by Geoff Sant, and was published by Del Rey in December 2006.
The story centers around two rival ninja clans; the Iga and the Kouga; whose no-hostilities treaty is lifted by retired shogun Ieyasu Tokugawa to settle a succession dispute within the government concerning which of Ieyasu's grandsons is destined to become the third Tokugawa Shogun. Due to years of selective breeding, the members of Kouga and Iga have all developed inhuman abilities at the cost of several of them being born physically disfigured or otherwise abnormally mutated. At the center of the conflict is Kouga and Iga's two young heirs; Gennosuke and Oboro respectively; who had fallen in love in the hopes of not only bringing their clans together in peace but also to mix the bloodlines of their families so as to undo the genetic damage endured by both. The novel traces the course of the conflict as both clans endure heavy losses and ultimately bringing Gennosuke and Oboro to face each other on the field of battle.
- Kōga Ninpōchō (甲賀忍法帖, 1963), a manga by Haruo Koyama.
- Kōga Ninpōchō: Aratame (甲賀忍法帖・改, 2003), a manga by Torao Asada.
- Basilisk: The Kouga Ninja Scrolls (バジリスク 〜甲賀忍法帖〜, Bajirisuku ~Kōga Ninpōchō~, 2003), a manga by Masaki Segawa.
- Basilisk (バジリスク 〜甲賀忍法帖〜, Bajirisuku ~Kōga Ninpōchō~, 2005), a TV anime series produced by GONZO based on Masaki Segawa's manga.
- Shinobi: Heart Under Blade (忍, Shinobi, 2005), a movie directed by Ten Shimoyama.