Sekai de Ichiban Ani Shiteru

Yori, a second-year high school student, unexpectedly begins living with Seki, the son of her mother's new husband, who is a second-year university student. Upon visiting Seki's apartment, Yori encounters a half-naked, intimidating man who, to her surprise, becomes overly attentive toward her. Despite his flamboyant and affectionate behavior, Yori finds herself unable to dislike him.