Yousuke Koiwai

Koiwai is Yotsubas adoptive father. The circumstances of her adoption are obscure he tells Fuuka that without intending to he found himself taking care of her while somewhere overseas but gives no other details. Though he acknowledges Yotsuba is a bit odd he can be offbeat himself. He is depicted as something of a slacker he habitually wears an undershirt and boxer shorts when working at home during the summer and apologizes more than once for being irresponsible. He works from home as a translator though what languages and materials he translates is unknown. Regardless of his skills as a parent Koiwai tries to be a good father to Yotsuba.