Ryotaro and Haru, both aged 15, discover themselves caught in a love triangle with Mirei, a girl they both hold dear. The trio steps into high school, and one fortuitous day, the two companions encounter Mirei outside the school premises, thoroughly enamoured by her. Serendipitously, she happens to be in their class, and to their astonishment, Mirei is an accomplished lover, unlike Ryotaro and Haru, who are complete novices in matters of the heart.