Gyaku is one of the Nine Characters that Appeared in Handmade Software's Kasumi Ninja for the Atari Jaguar.
Gyaku is the main enemy of the Game, and The Final boss of the game. Gyaku, Along with Senzo, are just Palette Swaps of Habaki. Gyaku, however, can turn into his True Form, and Giant red Reptilian/Humanoid monster looking creature...
- Lord Gyaku is the final boss of Kasumi Ninja. One of the eldest ninjas, Gyaku went berserk and killed all of the other elders on Kasumi island and proclaimed himself Lord of Kasumi Island. It is said that Gyaku is possessed by spirits from the Demon World. With the Dragon Cloud Temple also in his possession, Gyaku is planning his overthrow of the Island. The Dragon Cloud Temple is said to have a portal to the Demon World, and with such awesome power, Gyaku plans to rule not only Kasumi Island, but the world. If the player does not use a death move on Lord Gyaku during the final battle in single player mode, Lord Gyaku will transform into "Demon Gyaku", a stronger version of Lord Gyaku that resembles a Red Frill Lizard Humanoid Demon. Defeating "Demon Gyaku" will reward the players with the "Best Ending." It is also possible to play as Gyaku with a secret code, whereupon he replaces Senzo and Habaki in the Versus Mode.