Oba no Shinshitsu

Kenta is an ordinary uni student, that due to his parent going overseas to work he is sent to his aunt house and her daughter that lives all alone. He loves his cousin Reina who is two years older than Kenta. One day, when he smells Reina's underwear secretly, Marina, who is Reina's mother, turns up. She threatens him to have a sexual relationship with her... Kenta is becoming her sexual slave gradually struggling between the love toward Reina and sexual desire toward Marina.