Gemma is the leader of the Eight Devils of Kimon, and you'll be hard pressed to find a more dangerous opponent. Desiring to rule all of Japan as a 'Shadow Shogun,' Gemma is evil, ruthless and totally amoral. Anyone crossing him had better be sure about their skills, because his powers are more than enough to win almost any fight.
Gemma's main goal in life is the acquisition of power. He's smart enough to realize that he can never be the man on the throne, so he will settle for being the true power behind the throne (a.k.a. the "Shogun of the Dark"). To achieve this end he will kill anyone and everyone required, sacrifice his own team members, and otherwise undertake any actions he thinks are required, all without a second thought as to who might be harmed in the process. In the course of Ninja Scroll, Gemma either kills or causes to be killed an entire village, the Chamberlain of a local clan, an entire force of ninja, a troop of soldiers from the local clan, several members of clan Toyatome (who wish to depose the current Tokugawa Shogun), and the kunoichi Kagero.
Quote: "My dream is different. ... I'll use [the gold] to organize the most powerful army of ninja ever. ... Meaning the true Shogun of the Dark... will be me."
Aside from his incredible physique and fighting prowess, he also has mastered the technique resurrection. A very powerful and ancient mastery over the mystical arts Every wound an Immortal obtains quickly heals and disappears, healing is performed by a small Quickening flashing across the wound. Since they are immune to disease and stop aging after becoming Immortal, they can live forever and they only die when they are beheaded. This technique mimics that ability with one added bonus. Think of it as some kind of backup. He burns his memory, body construction and everything else about him into the akashic field. If his acting body dies or is injured in any way, in time his life energy will coalesce into mass reforming his body restoring his soul. Even if his head is cut off he will eventually resurrect. Unfortunately when his body dies he soul still has to go through the process of reincarnation. It is impossible for him to die there is no growth there is no decay there is only the etheral pause. Of course, he also has a few other tricks up his sleeve. He can alter his body to assume virtually any human form, recreating not only their looks, but their voice and mannerisms as well. The armor he wears on his arm is used as an active defense in combat, blocking sword strikes with ease.
Gemma is big, very big, standing well over six feet in height and is massively muscled. He has short black hair, dark eyes and a very deep voice. His costume is the most 'modern' of any character in Ninja Scroll, consisting of a purple sleeveless tunic with a deep v-neck, trousers and boots. His left shoulder and arm is covered by a series of articulated plates. The base of his neck is marred by a broad scar that goes all the way around.