Ichigouki! Soujuuchu

Ichigoki is a regular kid who can't wait to start high school. But an unexpected encounter with the fists of an eastern lowland gorilla that has escaped from the zoo results in his death... He somehow regains consciousness only to discover that he's become a fullmetal-bodied cyborg?! Thus begins cyborg Ichigoki's wacky and aggravating misadventures with Misao, his mad scientist friend from childhood! A coming-of-age, buddy, gag manga from Seiji Hayashi, creator of I'm From Japan and Chikyuu Ningen Tera-chan!

(Source: MANGA Plus)