Yuri Koigakubo

Yuri is the twenty-nine-year-old homeroom teacher of Ryūji's class (though she turns thirty in the fifth volume of the light novels). She likes to do things at her own pace and is timid towards Taiga's way of speaking out. Since her twenties are almost over, Yuri is in a hurry to get married soon and she even tries to dress well so as to be able to get into a relationship quicker. After she becomes thirty without getting married, she develops a twisted and depressed personality, which does not help that when Taiga talks about her, she emphasizes her single status.

She is fairly concerned over the well-being and grades of her students and tries her best to help them. During the Winter, she banned Haruta from Christmas Activities to get him to study for exams.