Kosuke is a neighborhood cat sharing territory with the extraterrestrial cat Nyan. He appears as a greenish Siamese cat and interacts with local feline residents like the elderly Professor, the Persian cat Momo, the calico Anko, and Anko's two kittens. His routine involves scavenging for food, especially school lunch leftovers. During one such scavenging attempt, crows attack Kosuke, leading to intervention by Nyan and the wandering Ryuji to resolve the conflict. Despite their aid, crow assaults on the neighborhood cats escalate afterward, endangering their sanctuary in a local park. Kosuke contributes to the communal challenges faced by the cats as they navigate these environmental threats alongside Nyan.