Yuuta has always been pushed around by his childhood friend Ran Himeno, who usually wears a blank expression and is hard to read. One day, she suddenly asks him to be her sex practice partner, saying she's found a boyfriend. Yuuta, who has feelings for Ran, can't bring himself to refuse and agrees to help. However, Ran has a personal rule: she won't kiss anyone except someone she truly likes, so she won't allow it with Yuuta. As the emotionless Ran gradually discovers pleasure, she begins to make lewd sounds and show erotic expressions. Witnessing her transformation, Yuuta finds his emotions overwhelming and can no longer hide his true feelings…!