Japan’s two smallest mobile networks, Softbank and Emobile, are reportedly joining forces to offer mobile data services in an alliance that could further threaten the dominance of their two larger rivals, NTT DoCoMo and KDDI. According to a report in Japan’s Yomiuri Shimbun, Softbank is planning to launch as an MVNO on Emobile’s high-speed data network, a deal that the newspaper says will be the world’s first such agreement between two network operators. Softbank is reported to be planning a flat-rate data plan service that will be priced around JPY4,980 (US$55.6) per month, similar to the two-year contract currently offered by Emobile, which is believed to be the lowest-priced data plan in the country. Softbank currently offers only a pay-as-you-go plan for mobile data, the report says.

Softbank has already proven to be a serious competitor to NTT DoCoMo and KDDI, and has consistently outperformed its larger rivals in terms of subscriber additions over the last two years. Meanwhile, Emobile, which launched in March 2007, is focused on providing HSPA services via a data-centric business model and claims to have already attracted a customer base of around 1 million. Chairman and CEO Dr. Sachio Semmoto told delegates at the GSMA Mobile Asia Congress last year that Emobile was on track to report its first profit in 2009. According to Yomiuri Shimbun, the planned tie-up between the two operators will allow Softbank to offer data services without having to make additional large investments, while Emobile would receive fees by leasing its network to Softbank.