Meijyou

One day, a beautiful girl at school, Otsuki Roonue (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 Otsuki, is stabbed and falls into the sea of blood. When the remaining Otsuki is about to be raped, the school principal's son, Oborozuki (16), appears. With his help, Otsuki's chastity is protected, and Hoshikai's life is saved. However, Oborozuki did not intend to help them for free. Instead, he threatened Otsuki on the condition of "being his woman for a week", and Obiyue had no choice but to agree to him. But there were conditions for this help. That is, Otsuki will become Oborozuki's woman for a week. Otsuki agrees in order to get out of her predicament, and above all to help Hoshikai. After school, with Hoshikai in the hospital, Otsuki is called to meet with Oborozuki. She begs to release her from the agreement but discovers how eager he is to take over her body. (Source: AniDB)