Yuuzuki Kiryuu

She is Mikazuki's older sister, the new teacher to Gakushū Senior High and homeroom teacher to Keita and Miharu, who in an earlier chapter was a clothing store clerk because she liked western style clothing. Through bad timing and unaware that Keita and his sisters are not related by blood, she believes that he is a deviant who dates multiple girls while having an incestuous relationship with his sisters. She becomes excited by her exaggerated ideas of what he and his sisters do at home or with other girls.