I don't know if they are of the custom of sex only for procreation, but Jii man sure fiddles his diddle a lot. I don't like to think about it but my grandparents were still going at it at 86 and 80 as I found a couple of bottle of ky when i was looking for toilet paper... I know my grandpa was like Jii-sama, but he preferred to only masturbate in vaginas