Kiki, a stunning beauty who always rocks midriff-baring fashion, has an unusual problem—she can’t have sex with men. Why? Because back in middle school, her junior Nakaba did something that left her able to feel pleasure only through her navel! Determined to punish the one who "ruined" her body, Kiki pays a visit to Nakaba—who, as fate would have it, has become a navel researcher!? A bizarrely sexy and totally off-the-wall romantic(?) comedy kicks off!