Iwanbou is a large, clumsy individual who uses his considerable size, strength, and the ability to trap weapons within his flab to his advantage. He is portrayed as unintelligent, participating only minimally in the battle of Aoiya, where he mostly grinned foolishly without speaking or taking significant action. His last known location was on a cliff outside Kyoto.
However, as revealed in the Jinchū or "Revenge" arc of the manga, Iwanbou is actually a mechanical puppet, a primitive mech controlled by Gein, a puppetmaster. Gein reappears in this arc as one of the six comrades, now controlling a more dangerous version of Iwanbo. This new form plays a crucial role in Enishi's plan for revenge.
(Source: Wikipedia)
