Yoshino is the mother of Kyousuke and Kirino. Her role in the family is pretty neutral; however, she often takes Kirino's side when arguing with her husband, Kousaka Daisuke. She has a rather sarcastic yet playful personality. She enjoys making fun of Kyousuke, especially concerning his porn collection. Kyousuke suspects that she goes through his porn collection checking for new additions every time she cleans his room. However, she doesn't seem to mind that Kyousuke owns porn; in fact, she finds it somewhat amusing.

She will always cook curry rice for lunch and dinner. Kyousuke finds it strange having almost curry rice every day of the week. Probably, it is the easiest dish to cook.