Prepaid SIMs come in quite a few varieties, but what I’ve realized after trying several is that the place of purchase is extremely important. Especially whether you can buy a SIM at a convenience store makes a huge difference in emergency situations.

The easiest convenience store SIM to get is the IIJmio JAPAN TRAVEL SIM. It’s available at Lawson, MiniStop, Don Quijote, and other stores, so it’s very helpful if you need one immediately. If you go with an eSIM, you can start using it in 5 to 10 minutes, which is also quite convenient. However, the downside is that the price is a bit higher.

On the other hand, if you’re okay with options outside of convenience store SIMs, your choices expand. HIS Mobile offers unlimited data for 30 days at just 3,512 yen, which is cheap, and Nippon SIM for Japan provides 50GB for 4,480 yen, offering good cost performance. But these are only available through e-commerce or specialized websites, so you need to order in advance.

If speed is your priority, JAPAN PREPAID SIM (Parrot Beak) was the most stable. Since it’s a direct SoftBank line, it remains fast even during peak congestion times. However, it costs 6,480 yen for 50GB, which is relatively expensive.

In conclusion, if you need it immediately, go for a convenience store SIM; if you have time, order a cheaper one from an e-commerce site in advance; and if speed is the top priority, choose SoftBank line even if it costs a bit more. The best approach depends on your personal priorities.