Grope: Yami no naka no Kotoritachi - Episode 1

A school in the middle of the school day. Earthquake. Ruins and four survivors. Two boys and two girls. One horny boy forces the first one, then the second girl to have sex. But they both like the second guy, so they lightly resist the first guy, while feeling a little remorse in the process. The exits and stairs are blocked, rubble and broken glass everywhere, there's no food or water, and the corpses of classmates can be seen in the piles of stones. The place is a literal ruin, but that's okay, in hentai being horny is a more important business.