After witnessing Saitama defeat Mosquito Girl, Dr. Genus becomes interested in Saitama's power and sends some of his creations to retrieve him. After Genos visits Saitama's apartment, one of Dr. Genus' creations, Kamakyuri, busts through Saitama's roof and is swiftly killed by a ticked off Saitama. Outside, Genos encounters Armored Gorilla and fights him.
Armored Gorilla attacks Genos but misses, and Genos counters with a kick before jumping back and charging. Armored Gorilla tries to swat him, but is blocked. Armored Gorilla then charges at Genos, with Genos dodging and performing a failed counter with his incineration cannon which doesn't affect Armored Gorilla at all. The final scene shows Armored Gorilla defeated by Genos.
After this battle, Saitama and Genos are told about Dr. Genus and the House of Evolution. Saitama then decides to go there right away because he thought there was a sale the next day. Before leaving, Genos asks Armored Gorilla about the House of Evolution's cyborgs in an attempt to find more information about the mad cyborg that destroyed his town as a child. Armored Gorilla states that he is the only cyborg there.