Hi. It’s possible to buy pay-as-you-go SIM cards directly from Japan’s major mobile providers like SoftBank and DoCoMo, but you can usually get a better deal (and experience) with an MVNO. This stands for Mobile Virtual Network Operator, and their SIM cards are generally the easiest path to getting online when traveling in Japan. MVNOs are not strictly their own carriers; they piggyback on existing big networks to offer some great deals.
Prepaid U-mobile, OCN and Rakuten SIMs are among those you can buy on the ground in Japan. Other options include BIC Camera SIMs and IIjmio’s Japan travel SIMs. However, a provider called Mobal offer perhaps the best deal by far—and unlike many other short-term Japanese SIM cards, they give you access to voice and SMS in addition to data (the rest are data-only). They have 30-, 60- and 90-day packages with 7GB of fast data, and they offer full English support. They also have free worldwide shipping, so you can get your Japanese SIM sorted before you touch down. You can arrange airport pickup at Haneda, Narita, Kansai, Fukuoka, Sendai, Nagoya and even Singapore if you prefer. You can also collect them in downtown Tokyo or Osaka.