One of the elderly tenants of the housing complex, he is often seen with Taka and Yoshiken. Koba appears to have been some kind of handyman or tinkerer, as in episode 1 he says he has fixed everything from appliances to warships. He has a wife that now lives in a rest home apart from him. Like all the elderly tenants, he shows affection for Kimi and dotes on her constantly.

(Source: toonami.fandom.com)