"Have sex with me right now. If you don't, I'll pick up the phone and start dating him!" Kyosuke and Machi are college students who have been in the same class since middle school. Since their parents were often working late hours, they became inseparable friends. One day, Kyosuke teased Machi just like usual, asking her, "Why don't you start dating?" But Machi responded with something totally unexpected...!! Machi had become so important to Kyosuke, he didn't want to lose her. If he got in a romantic relationship with her, he might lose her love one day. Kyosuke preferred to stay as just a friend. That's what he thought, and yet...