Japan’s new fourth operator Rakuten Mobile today (8 April) launched its full-blown cellular service in Japan, throwing down the gauntlet with its low-cost price plan which threatens to spark a price war in the market. With the backing of e-commerce giant Rakuten, the newcomer unveiled a single price plan costing JPY2,980 (USD27.4) per month for ‘unlimited’ voice calls and mobile data – available in urban areas where its own network is live, including Tokyo, Nagoya and Osaka. Rakuten Mobile’s offer is a dramatic saving on the roughly JPY7,000 per month charged by the old guard, NTT DOCOMO, KDDI (au) and SoftBank Corp, for similar high-volume data plans. Kyodo News notes, however, that outwith its own (limited) network footprint, the new fourth mobile network operator is leasing capacity from KDDI to achieve nationwide coverage, and its offer is limited to 2GB of data in those areas. Meanwhile, from 22 April Rakuten hopes to boost the cap to 5GB in those areas, and it plans to expand its own network through the country’s 47 prefectures by March 2021. To boost uptake the operator – which first dipped its toe in the domestic mobile market in October 2014 as an MVNO – is offering ‘voice and data services free of charge’ to some three million subscribers in the first contract year. It is accepting applications through its website.