Hina's mother and Kenta's father just remarried each other, so they both became sisters. Hina appears to be an extremely smart girl but is very shy. She was chosen to be the representative to give a speech at the university graduation ceremony. Kenta is also shy like Hina, but he is not as smart as his stepsister. Therefore, his parents asked Hina to tutor Kenta to help him pass the upcoming university exam. But Hina has a secret that others don't know, which is that she loves sex! Every day Hina "accidentally" rubs her breasts against Kenta's body, pulling off her panties to reveal her pussy to him. Even when Kenta saw her having sex with her boyfriend, Hina deliberately let him see more clearly. Unable to resist their stepsister's charm, the two secretly fucked each other right in front of their parents! Of course, their parents didn't find out because Hina used her long dress to cover it. But even so, both of them still had to try to limit their noise and appear as normal as possible. The exciting feeling of being discovered at any time made Hina feel extremely horny. She even makes Kenta fuck her bare and cum all over her pussy! And from then on, in front of her parents, Hina acted like an older sister who cared about her younger brother, trying to help him study. But in reality, the two are secretly fucking each other non-stop...