Kouko Ibuki (伊吹公子, Ibuki Kōko?) is the older sister of Fuko Ibuki who is a former art teacher at the Hikarizaka Private High School, and she treats everyone kindly. Kouko is one of the familiar faces in Furukawa Bread, the Furukawas' bakery, and Nagisa Furukawa admires her very much, being her former art teacher. She is married to Yusuke Yoshino and he is the major reason why Fuko still exists as an ikiryō in Tomoya Okazaki's school, despite still sleeping in the hospital.
Following her marriage, it is presumed she takes her husband's surname, which now makes her Kouko Yoshino (芳野 公子, Yoshino Kōko?). However, this name is not used in Clannad.
