mr. koiwai
よつばのとーちゃん (Yotsuba's Daddy) / 小岩井 ([Mr.] Koiwai)
A character from Yotsubato!
A freelance translator and Koiwai Yotsuba's adoptive father, whose given name may be a potential spoiler.
In comic vol.13, his mother called his given name, Yousuke(葉介).