Tsuma no Biniku o Masaguru Chichi no Futoi Yubi ~Shiranu Ma ni Chichi no Mono ni Natteita Tsuma wa, Yorokobi no Aegi to Tomoni Koshi o Uneraseteita~

After I married my wife, my mother passed away from cancer. My father fell into a deep depression, so I couldn't leave him alone and we moved in together. One night, after my promotion, we celebrated with drinks. My father got drunk, and my wife, normally a light drinker, became affectionate and we ended up making love while he was nearby. But that night only made his depression worse. Then, a week-long business trip was scheduled...