Mayu Sugino's an office worker who loves sweets. She's secretly dating her coworker, Ryo Fujii, who hides his sweet tooth at the office. A trip to the beach is planned as a staff outing, which means bathing suits are a must. Ryo suggests a very special workout regimen to lose weight: Kissing! Doing it from behind!! On top!!! Will all of this physical activity get Mayu the results she's after...!?