Tokyo fundoshi geisha (1975)

A young geisha/prostitute working in Tokyo's entertainment district earns a measure of reknown through her powerful vaginal muscles. This newfound fame, however, also earns her the enmity of a rival geisha house. The two houses choose to settle the dispute through a series of athletic contests between the young star and the rival house's main attraction, with the backing of the houses' wealthy patrons as the prize.