Shy and reserved girl, Sayo. Desperate not to lose her first boyfriend, she's always obeyed his every word. One day, when visiting his room, Sayo is asked by him to wear a swimsuit. Blushing with embarrassment, she undresses and changes into the swimsuit to fulfill his wish. Though slightly uneasy exposing herself in front of him, she finds herself drawn into his words. This moment becomes the turning point that deepens their relationship.