"I can't get it up…? What's wrong with my body…!!?" On the day after his birthday, naughty high-schooler Yuki finds out an astonishing truth: he's not actually related to his older twin brothers, Rai and Mei. Has the shock of this discovery made Yuki impotent!? Yuki's feeling down and is worried about his erectile dysfunction, but the silly, macho Rai and smart, caring Mei offer to fix his problem by bathing with him. The three of them in the bath together reminds Yuki of when they were kids, but suddenly, Rai's hand reaches for Yuki's crotch! What's worse is, Yuki, who couldn't get an erection from looking at girls, gets rock-hard from his brothers' foreplay!