Japanese e-commerce giant Rakuten is moving into mobile messaging after it announced a $900 million deal to buy Viber, the Cyprus-based mobile voice and chat messaging company that claims 300 million registered users worldwide.

A statement from Rakuten explains that Viber “perfectly complements” its digital strategy, which has seen the Japanese firm buy up a range of companies — including tablet maker Kobo and global video site Viki.

“As Rakuten aims to become the world’s number one Internet services company, this acquisition will enable Rakuten to penetrate new markets with multiple digital content offerings, in combination with its e-commerce and financial services platforms,” the company says.

Rakuten has firm grip on the e-commerce space in Japan, where it offers a range of marketplaces for all manner of goods, and it has branched out into banking and financial services, however it is still to replicate its dominance overseas.

The deal for Viber is interesting because — particularly in Asia — messaging apps have become platforms for delivering a range of services, including Rakuten’s specialty: e-commerce. There is also potential for Viber to be used to deliver a range of other entertainment services — such as programming on Viki — and we might see it pre-loaded to Kobo devices.

Irrespective of anything else, the deal illustrates Rakuten’s desire to break out internationally, and the value of messaging services as strategic platforms.

Hiroshi Mikitani, Rakuten Chairman and CEO, said in a statement:

I am tremendously excited to welcome Viber to the Rakuten family. Viber delivers the most consistently high quality and convenient messaging and VoIP experience available. Additionally, Viber has introduced a great sticker market and has tremendous potential as a gaming platform.

Simply put, Viber understands how people actually want to engage and have built the only service that truly delivers on all fronts. This makes Viber the ideal total consumer engagement platform for Rakuten as we seek to bring our deep understanding of the consumer to vast new audiences through our dynamic ecosystem of Internet Services.

The news comes days after Viber was linked with a $400 million acquisition from an unnamed Asian company. Speaking at the time, Viber CEO Talmon Marco denied knowledge of a deal. Viber has not raised outside funding, so the deal is a huge win for its founders.