Japanese ecommerce giant Rakuten is stepping up its U.S. advertising play.

The company's Rakuten Marketing division has acquired Deep Forest Media, an automated ad-buying platform which will make use of Rakuten's e-commerce data. The data will be used to tie user identity across devices, helping marketers apply the same targeting on mobile and desktop, which is difficult today due to the poor functionality of cookies on mobile devices.

"For our advertisers, it means that we can start to put together a more strategic marketing plan that allows us to reach consumers on different devices at different times with different messages," said Rakuten Marketing CEO Tony Zito in an interview with Ad Age.

This marks the first time Rakuten Marketing is using the company's e-commerce data, though it will only utilize its login data, not the more valuable purchase data which can be a proxy for intent.

The company is also planning to pull in data from other Rakuten properties, which include a number of mobile apps.

The move is just a start of a larger effort, according to Mr. Zito, who said the company is looking at ways to integrate more of its data down the road. The login data will be anonymized.

Even without the purchase-intent data, the ability to create unified user identities should give Rakuten Marketing the ability to compete with companies using login data to more accurately target ads. Those companies not guessing at user identity on mobile -- such as Pandora, Twitter and Facebook -- are garnering a high percentage of the dollars flowing to the medium.

Deep Forest, a 37-person company based in Palo Alto, Calif., was founded in 2012. A modified version of its data-management backend will be used to house its data.