Soushi Soumai ~Oya no Inu Aida ni...~

Maina is my little sister. She's always been cute to me, but lately she's so cute it's making me hurt. Guys at school are falling over themselves to try and win her. To steal her from me. Our parents are going on a 3-day vacation. The next 3 days, it's just us! Maina is all mine.