In this adult sibling role-play, Kotone Toa used to be the sweet little sister who would say, “When I grow up, I’m going to marry you!” Lately, though, she has started avoiding me. She must just be playing hard to get—there’s no way she could really hate me. Then one day I catch her happily talking to someone on the phone. Has she got a boyfriend? Before my beloved adult sister becomes some random guy’s woman, her big brother will be her first. We can lose our virginities together.