Gein is the last remaining descendant of a small group of people who mastered the art of mechanics in the Middle Ages.
Gein unlike others of the comrades just wants to test out his creations and needs to be around men of battle to do it since according to him, the forefront of technology is always in battle. This is also the reason why Gein joined Shishio.
Gein first joined Shishio's Ten Swords (Juppongatana) disguised as Iwanbō and later, Enishi's Six Comrades.
Once Shishio was dealt with, Enishi met Gein and had him organize the first meeting between the Six Comrades and acquire a mansion for them to stay at. For Enishi's Jinchū he creates a corpse doll of Kaoru to fool Kenshin into thinking she had been killed by Enishi, he considers this his masterpiece.
When Gein gets to Tokyo he goes to the graveyard to get his Kaoru doll where he runs into a trap set by Aoshi, who had figured out that the corpse was a fake. Aoshi kills Gein after discovering where Kaoru was.
A short thin old man but by wearing a skull mask he looks like a very scary figure. This is also his most striking feature.
Skills and Abilities
He is actually an old man yet he is very strong due to controlling his heavy puppets for so long. The diamond edged steel wires he uses (Zankosen) to control his puppets can also be used as a weapon as they are sharp enough to cut flesh and break bone.
He creates puppet like suits out of the corpses of dead people, most notably the Iwanbō series.