I think many people are currently confused about choosing a budget SIM with 1GB per month, but it really depends heavily on your usage.

Since I've tried various options myself, I think it's best to consider roughly three patterns. First, if WiFi is your main environment and you only use your phone a little when you're out, a 1GB/month budget SIM is sufficient. The Japan Communications SIM using the Docomo network costs only 290 yen per month, which is a great deal. There is an initial fee of 3,300 yen, but if you use it for a year, you'll recover that cost. However, speeds drop during lunchtime, so it's suitable for people mainly doing text messages or light browsing.

Next, if your data usage varies from month to month, consider povo. It has a base fee of 0 yen, and you buy only what you need. 3GB costs 990 yen, so 1GB would be even cheaper. Since it uses the au network, speeds are stable, and adding data is easy. For people with fluctuating monthly usage, it's one of the most user-friendly budget SIM options.

The third option is for people who make a lot of calls. Rakuten Mobile offers unlimited domestic calls, and 3GB costs 1,078 yen. It can be a bit difficult to connect underground, but if your main use is calls, it shouldn't be a problem.

Ultimately, when choosing a budget SIM with 1GB per month, the most important thing is to clarify your usage. Don't decide based solely on price—consider also the data speed and whether calls are included. That way, you can make a choice you'll be happy with.