Gennosuke was the older brother of Ryuugen.

Kacchu no Senshi Gamu

Because of his violent nature and lust for war, Gennosuke's father decided to teach Ryuugen the art of training ganins instead of Gennosuke (The art was usually passed on to the oldest son). Gennosuke was killed in battle several years ago.

However, he was brought back to life by the evil Gama who inserted a pin in his brain. This pin made Gennosuke into a zombie, controlled by Gama's minion Belmond. Gennosuke is sent out to kill Ryuugen, however he doesn't succeed as he is “killed” by Gamu who destroyed the pin in his skull. Thereby removing Gennosuke’s ability to be a living dead.