Shota and his family visit his cousin Miyu's summer villa, which has a private pool. Shota needs to practice swimming for his school summer homework, so Miyu agrees to teach him. However, once she changes into her swimsuit, Shota becomes completely distracted by her stunning figure and her amazing big breasts, causing his cock to get hard and throwing off his balance so he can't swim properly. Noticing Shota's awkward state, Miyu feels embarrassed but continues doing her best to teach him. Yet, her actions carry hints of something deeper than mere instruction.