One day, a beautiful girl at school, Long Yueh (17), was attacked by two thugs while on a date with her boyfriend, Hoshikai Singhai (17). Her resistance is in vain and Hoshikai, who tried to protect Long Yueh, is stabbed and falls into the sea of blood.

When the remaining Long Yueh is about to be raped, the school principal's son, Chōng Rì (16), appears. With his help, Long Yueh's chastity is protected, and Hoshikai's life is saved. However, Chōng Rì did not intend to help them for free. Instead, he threatened Long Yueh on the condition of "being his woman for a week", and Obiyue had no choice but to agree to him. Long Yueh agrees in order to get out of her predicament, and above all to help Hoshikai.

After school, with Hoshikai in the hospital, Long Yueh is called to meet with Chōng Rì. She begs to release her from the agreement, but discovers how eager he is to take over her body.