[Sangetsu]

It's not just onsens where tattoos are not permitted, you are also unable to use public swimming pools, or go to water parks. You'll see signs in front of these places telling you that people with tattoos will not be allowed in.

If you want to use an onsen, such as at a ryokan, and have a tattoo, you can always reserve a private bath. Ask as soon as you check in so you can book a good time. This is also a good option for couples who would like to bath together, or simply for those who don't care for the thought of bathing in public.