Oneesan wa Bushoumono

Synopsis

A loose T-shirt and barely visible hot pants. The tutor greeted him in loungewear that left me nowhere to avert my eyes, and mistook me—a seventh grader—for a second-grader! Not only did she have no sense of distance, but, neglecting my studies, she started playing weird games with me!? My exciting age-fraud days with the "sloppy-cute" lady tutor! (Source: Kodansha, translated)

Anime adaptations