He doesn't like cheating women, so he proposes to his best friend to set a trap to see if his new girlfriend is faithful. The rules were that if they exchanged contact information or came home with him, he was out, but he fell for Akari, who showed him her innocent cuteness, and Akari responded to his feelings by not only crossing the line, but also cumming inside her. The two of them got carried away from what was supposed to be a simple experiment and ended up cumming inside her again and again.