>>2805119
Store like Don Quijote will sell packs of waterproof tattoo covers or tattoo seals. However, if you need a bigger tattoo cover, just use Amazon Japan and set your pick up location to the convenience store nearest to your hotel room.

https://www.timeout.com/tokyo/shopping/how-to-cover-up-your-tattoos-when-visiting-an-onsen-or-pool-in-japan