Genki is rather timid.
He joined Parabellum after being freed from the Kirika Empire's slave army.
After seeing that Parabellum was only led by an Ogre (Ogarou) he probably decided to rebel along with Fuuki and Netsuki and take the command. But they were easily beaten...
Rou decided to use his Ogre Orb to make some experiments.
Later, he took part in the First Group of the First Expedition led by Rou along with Fuuki and Netsuki with the objective to reach Trient and Osvel.
At that time, he was considered to be stronger than his 2 companions.
Rou teached him Ju-jitsu.
During a friendly competition with adventurers (with Rou charging admission fees), 1 silver plate (10,000 gold coins) was offered as reward to anyone that could defeat him.