In a room of an apartment building lies the yoga studio "Uosonanda Yoga." Today's regular class is in session, but the instructor isn't the usual Uosonanda sensei, who has returned to India. In her place stands Hikaru sensei, a young Japanese woman whose youthful, tight figure and F-cup body quickly draw attention. By chance, Takuto runs into her on the street and instantly falls for her charm, prompting him to start attending her classes. Hikaru sensei demonstrates poses in a snug leotard, and Takuto becomes increasingly aroused by the visible nipples and crotch contours beneath the fabric. Because he's stiff and struggling, she diligently guides him with close physical adjustments, lightly touching his body. Unaware of the effect she's having, she continues teaching earnestly. But as their physical contact intensifies, Hikaru too begins to feel subtle arousal, and the lesson gradually escalates into something far more intimate.