This kind of card completely meets your needs, (mainly non-social people like Japanese high school students, who don't have too many phones, but like to play mobile phones, with a lot of traffic) Usually this kind of Gean card, You only need to call about 19 yen (about a little more than 1 RMB) and you can have 7G traffic (4G high speed, you can continue to surf the Internet after 7G, but the speed is very slow)
It seems that you can't make a phone call (you can receive short messages, in fact, you can make a voice call similar to app)
It should be noted that you need to prepare a mobile phone without the sim card area, and you have to pay a fee in advance for 3 months (in addition,