Konna no Zenzen Erokunai!

A beautiful woman suffers from a bizarre condition—she can't feel any sexual arousal from having her body touched, except through her belly button. To make things worse, her belly button is always exposed, making daily life a constant source of discomfort and frustration. Determined to take back control, she decides to confront the man from her past who made her this way. But when she finally tracks him down, she discovers he's become something completely unexpected: a full-fledged belly button researcher.