The two of them played a "secret game" when they were kids. Yasuhiro's always thought he was to blame for twisting his cousin Yuma's sexual orientation, and he started avoiding Yuma at a certain point. But one day, Yuma turns up at Yasuhiro's apartment and insists that wasn't the reason for his orientation. On the contrary, Yuma lusts after his body every time they meet. Thinking he mustn't get swept away, Yasuhiro uses his work as an excuse to escape Yuma's advances, but the impulsive Yuma closes in. Yasuhiro had always thought of Yuma as a kid, so when Yuma makes an unexpectedly "adult" remark, Yasuhiro can't help slapping him. And yet, Yuma still hasn't learned his lesson! What'll Yasuhiro do...?