In my experience.....(am about to have another in 2 hours) is that one or the other partners in crime will obliquely state a preference for things they would like to do. For example today, will no doubt entail visiting my partners favorite cake and chocolate shop.We will then go to a movie , and finally end up at one of our two places to close out the night. When one of us mentions "Onsen" it is more or less a statement that we will be heading to a local Hot Spring and rent our own private bath. Of course we both know the reason why we are going, we just never say it!(although I sometimes do )....We have now been seeing each other for 5 years and have yet felt the need to go to either a Karoke Box, nor a Love Hotel (we prefer nice hotels on points in foreign countries^ ).