My busty girlfriend was NTR'd and forcibly impregnated by my dad. (Mizono Kazuka, NTRH-002)

Koichi and Kazuka, a loving couple living together and even considering marriage, visit Koichi's father, Kunihiko, as a wedding greeting, only to be met with opposition. Completely shocked and disheartened by this unexpected opposition, Kazuka receives a text message from Kunihiko on her social media: "I'll keep it a secret from Koichi, but I'll tell you why they oppose the marriage." Kazuka goes to Kunihiko's house alone… where she is given tea laced with an aphrodisiac…