Kairaku onsenkyô: nyotaiburo (1981)

As rumors spread about a hidden treasure worth 300 billion yen buried somewhere in the hills near a local inn and hot spring a large number of people check in with two things on their mind… treasure hunting by day and sex hunting at night. The geishas at the inn have their hands full as the inn is fully booked. A shrewd rich tycoon makes an offer to the owner to buy the inn. But she dismisses his offer and names a much higher price. The tycoon is reluctant until news that some actual gold pieces have been unearthed. But is the timing of this “news” a little too convenient?