Naruko Yokoshima is a teacher at Ōsai Academy and serves as the advisor to the student council. She is one of the few adult characters who appears regularly in the series and is often addressed as Yokoshima-sensei. In appearance, she has short brown hair and brown eyes. Her personality is marked by a playful and often provocative demeanor; she frequently makes teasing or suggestive comments to the male students, particularly Takatoshi Tsuda, which lends a comedic tone to her interactions. Despite this, she takes her responsibilities as a teacher and council advisor seriously, showing herself to be intelligent and organized. She holds feminist beliefs and is not afraid to call out inappropriate behavior when it crosses a line, creating a dynamic where she both instigates and restrains the ribald humor of the student council members. Her voice is delivered in a notably deadpan, monotone style, which contrasts with the more excitable temperaments of the students. In her role, she oversees the council’s activities, occasionally joining school trips and events. She has a professional relationship with another teacher, Daimon-sensei, who is younger and less experienced but often helps keep her in line during school outings. Her motivations appear to center on maintaining an enjoyable yet orderly school environment, though her own sense of humor frequently undermines her authority. There is no significant personal development or change shown over the course of the series; she remains a consistent source of adult presence and risqué commentary within the student council’s daily life. Her notable abilities are not highlighted beyond her teaching and advisory duties.