Koisuru Succubus no Ikenai Jijou

Two twin girls, Oona and Hooru, visit Takeuchi Kou, a male porn star known for his skills. Despite their youthful appearance, they are succubi who survive by consuming sexual energy. Their goal is to be with Takeuchi, but their species prevents them from being with him. A method exists for a succubus to become human—by gathering "abstinence orbs." These orbs are created when Takeuchi teases the twins to the brink of orgasm without allowing them to reach it. A contest of abstinence begins.