Rei and Kyoko are close friends who met through their children, often enjoying meals and short trips together. Both women are in marriages that have fallen into a rut, and as they reach their prime, their sexual frustrations grow. One day, Kyoko, who works at an apparel company, receives a surprise in her employee discount purchase—a bikini. This sparks an idea, and the two begin spending time together in bikinis. Seeking relief from the stresses of daily life and eager to rediscover their own allure, their relationship takes an unexpected and intimate turn.