Search for public baths from the main pageAs you may already be aware, tattoos are taboo in Japan and most day onsen operate a strict policy regarding tattoos. Basically, if you’ve got one, you’re not coming in. Some go further to clearly stipulate that if you do enter the baths and have body markings (after all, who knows until you’re naked?) then you will be asked to leave. A minority of day onsen do allow tattoos but ask that they be covered, and an even smaller subset openly allow those with tattoos.
As most other countries do not have such a stigma against body markings (indeed, it might be a part of the culture), this can come as a bit of a surprise to some foreign visitors. Wherever possible, I’ve added the tattoo policy of the onsen to each post, and you can search for those day onsen that have no issue with tattoos via the main search page/bar. Given that my Filipino girlfriend has three tattoos, one of which is a little too large to cover up, it’s been something I’ve had to enquire about!
The only other thing I would mention is that even for those onsen which openly allow tattoos (in other words, do not even require that they are covered with a bandage), it is still culturally advisable to cover them up as other bathers might not be aware of that particular onsen policy.