Little Hole ~Ore no Musume ga Konna ni ... na Hazu ga Nai

Naoto is happily married to his wife, Saki, and works long hours to support his family. However, his young stepdaughter, Mion, has secretly lusted after him ever since they met, and starts to catch his attention. One evening, Mion slips into his bed at night, and the two begin to carry out a sexual relationship behind Saki's back.