Can you cover a tattoo with a sticker at a Japanese onsen?

Yes, if the bath allows it. Where stickers are accepted, it is usually for small tattoos. No national size limit is published: Japan Tourism Agency guidance suggests letting covered guests in, and each facility decides. The one size on record is a single sticker of about 8 cm by 10 cm, reported for the Hoshino Resorts chain by a secondary source. Large tattoos usually mean a private bath.

Adoption of the guidance is optional. In the agency’s 2015 survey of 581 facilities that replied, 56% refused tattoos, 31% did not and 13% allowed them if covered. One Hakuba venue’s sign (reported) says only small tattoos that can be covered with stickers are fine, and otherwise no entry. A sticker is a courtesy, not a right, and the venue can still say no.

• Book a private bath or a room with its own bath. Tattoos are not an issue there.
• If you want the shared bath, email the venue before you arrive and ask whether stickers are accepted.

• Skin-coloured and waterproof. Some places sell or give them out, so ask at the desk.
• Fit: one directory advises a patch that extends at least 1 cm past the tattoo’s edge, applied at least 30 minutes before bathing, with spares in your bag.
• Hakone Tenzan asks tattooed guests to cover up and admits only one at a time. The Kusatsu Gozanoyu FAQ says there is no specific refusal of tattoos at its three baths.
• For the other named baths, the official page publishes no tattoo restriction, so ask.