July 2017

There are two major kinds of mobile phone contracts in Japan. The first choice is a contract with Japanese three national wireless carriers which are NTT docomo, au, and Softbank. The second choice is a contract with Japanese Mobile Virtual Network Operators (MVNO) which do not have their own wireless networks. The MVNO operate on either the NTT docomo, au or Softbank networks. Generally, MVNO offers cheaper plans than carriers because they don't have to invest or spend maintenance costs in the infrastructures of wireless networks.

Coverage is not an issue with MVNO, as MVNO are covered under the same wireless networks of national wireless carriers. One of the biggest difference between carriers and MVNO is the data speed. In crowded areas or internet rush hours, MVNO tend to provide slower data speeds due to their contracts with national wireless carriers.

One more difference between carriers and MVNO is the minimum contract period, carriers tend to have a two-year minimum contract period, while MVNO only require one-month or one-year. Most of the prepaid SIM cards sold in Japan are provided by MVNO.