Courtesy of the largest Japanese carrier NTT DoCoMo, the miniscule paper roll serves several purposes. First, you can wipe your phone's screen with it to keep it pristine and hygienic, immune system be damned. Next, there is useful Wi-Fi login information, as these phone paper rolls are situated all over the Tokyo airport Narita.
Last but not least, for our international passengers, we have travel info and translation service app details, all on the back of the tiny toilet paper for your smartphone. Only in Japan. This surely beats Google's Pixel sweaters by a mile.