Even though UV-C sanitizers exist, they’re not always portable. Plus, you need to charge them pretty often, which can be a pain for travelers. In Japan, they offer tissues for removing smudge and fingerprint marks from your smartphone screen. After using, just toss the tissue in the trash, and continue on with your day. It’s called smartphone TP because it comes in toilet-paper-esque rolls.
If you pay attention to the wrapping, these tissue rolls also come with instructions on how to connect to free Wi-Fi. This is a great introduction to the country for those who need help with translations and have no way to get around.