Gemma Himuro (氷室 弦馬, Himuro Genma) is the leader of the Eight Devils of Kimon and main antagonist of Ninja Scroll. In Japanese, was voiced by the legendary seiyu, Daisuke Gōri, who also voivced Heihachi Mishima and Uighur.
Long ago before he led the Eight Devils of Kimon, he tricked Jubei Kibagami's comrades into attacking their friend. While escaping, Gemma was decapitated by Jubei himself, avenging his clansmen.
Somehow later on, Gemma resurrected himself and formed the Devils of Kimone, pretending to serve the Shogun of the Dark, a group of former Toyotomi retainers who want to take back what's theirs. Two days before the gold stealing operations were to go as planned, Gemma killed the chamberlain of the Mochizuki clan then impersonated him throughout the film.
This technique was shown when he murdered Kagerou near the end of the movie. Jubei was angered by the killing of his lover, then craves for Gemma's blood. After leaving port, Gemma reveals his plans to take over Japan to the Shogun of the dark and calls himself the real Shogun of the Dark.
After Jubei set the ship ablaze, he and his nemesis fight their final battle. After Jubei covers Gemma in gold, he prepares to leave but Gemma tries to take Jubei with him. Sensing this, Jubei yells for Gemma to "burn in [his] golden hell" then leaves Gemma to sink to the bottom of the sea with his dreams.