Watashi ni Karada, Utte Minai?

"That makes a grand total of 100 thousand dollars." After Tsukasa's mom is killed in a car accident, her dad becomes addicted to drinking and gambling. One day, he disappears, leaving Tsukasa with a debt of 30 thousand dollars. There's no way a student like Tsukasa could get her hands on that much money! Eventually, debt collector Reiko shows up, inviting herself into Tsukasa's home and telling her to pay up. She offers the young girl a way of getting cash fast: by selling herself to Reiko. "Want to sell me your body?" Tsukasa agrees without really understanding what that entails, and when Reiko moves in with her, their relationship suddenly takes an unexpected turn...

(Source: Renta!)