Google is working with KDDI Japans second-largest mobile-service provider after NTT DoCoMo, to provide a search service for mobile phone users in the Japanese market as of July. KDDI has more than 22 million mobile phone users, less than half of DoCoMo's, but its Au brand service is more popular among young Japanese people because of services such as music downloads. KDDI which uses the "au" brand name for its cellular service will offer the rebranded version of Gmail under the "au one mail" name. Like Gmail, the service will be accessible from both personal computers and cell phone screens.

A sample version of the interface revealed that the new service will look almost identical to Gmail but with the carrier's logo at the top. It will be offered at no charge to users.