London-based payments enabler Currency Cloud has closed an $18 million series C round, taking its total funding to $36 million since the company was founded in 2012.

The latest round was led by Sapphire Ventures, with participation from all of Currency Cloud’s existing investors, though one notable new investor has entered the fray — Japanese ecommerce titan Rakuten, which is participating through its Rakuten FinTech Fund.

Currency Cloud doesn’t often garner the same attention as fellow London fintech companies such as TransferWise or World Remit, but it’s Currency Cloud’s engine and application programming interfaces that help power the global payment mechanisms behind the aforementioned companies, and others.

Indeed, TransferWise has blazed a trail in the peer-to-peer money transfer space, essentially cutting out the banks to help users save money. Last year, the company announced a $25 million funding round, with big-name investors such as Richard Branson and Peter Thiel on board. With major clients such as TransferWise on board, Currency Cloud says that it now processes in excess of $10 billion in payments each year, across more than 40 currencies in 212 countries.

While Europe has been a major conduit for its success so far, Currency Cloud recently opened a hub in New York, and this latest funding round will help bolster its plans to dig deep into the U.S. fintech industry. The funds will be used to help support growth elsewhere in the world, too, as well as to boost its research and development initiatives.

It’s important not to underplay the significance of Rakuten’s involvement here too — this is a major scoop for Currency Cloud. Founded out of Japan in 1997, Rakuten has been expanding its global footprint through investments and acquisitions. Indeed, it has snapped up (since rebranded as Shopping in the U.S.), Canada-based ereader company Kobo, and a number of local ecommerce companies across Europe.

The Rakuten FinTech Fund was set up with the express purpose of investing in “disruptive financial services startups across the globe, with a focus on North America and Europe.”