I'm just a weeb-lord but from the JP I could understand; Chisato aka Sato (Blonde) & Takina (Black hair) are a lesbian couple. Sato wants a baby and asked Takina to go get cream'd by some guy to make the baby happen. Before this, Takina was a virgin and it's implied Sato still has her virginity. During the railing, Takina slowly begins to enjoy the D though she insists it's all just to get pregnant. At the end Takina starts telling Sato how roughly he fucked her and that she wants Sato to meet him as well so they can both have his baby. Something like that.... it's implied that Takina changed & was corrupted from the sex but I may have misunderstood. That's all I got.