How to solve the problem of mobile phone traffic when traveling to Japan?

A few years ago, there was no choice but to open international roaming. Later, with portable WiFi, renting WiFi is much cheaper than roaming, such as roaming the world and roaming Superman. The network is not blocked. Although I need to bring an extra device, I still put up with the thought of roaming. Nowadays, a billion-point global network card, just like a WiFi, feels that it can't stand the burden of WiFi devices. I used a billion-dollar card to go to Japan, and the effect was very good.