Travel to Japan, use a mobile phone number, is there a signal to Japan?

Call 10086 to open domestic and international roaming. This service is free. By the way, it's best to rent a portable Wi-Fi in advance, because Wi-Fi in Japan has not spread to all the streets with signals, and Google Maps is only available under wifi. Or choose mobile traffic. 4G traffic fee is the upper limit of 60 yuan every day, and it will not be charged if it exceeds the limit. If the time to go is short and the number of people is small, you can choose this one.