Japanese mobile and social gaming juggernaut GREE has recently taken a ‘strategic minority stake’ in mobile and Web-based instant messaging company eBuddy, reports Emerce.nl (in Dutch).

Jan-Joost Rueb, the co-founder and CEO of the Amsterdam company, confirmed the news to The Next Web in an email. Rueb declined to disclose the terms of the investment, which occurred a few months ago but wasn’t announced to date.

GREE actually also boasts an office in Amsterdam and just established a presence in London to boot.

You can hardly call GREE and eBuddy startups anymore. GREE, for one, was founded back in early 2004 and went public four years later. eBuddy was started under the name e-Messenger back in 2003.

GREE has been on an expansion rampage of late, social mobile gaming platform OpenFeint for $104 million, Korean social gaming company Paprika Lab and US-based mobile game developer Funzio for $210 million.

eBuddy, meanwhile, says it currently processes over 17 billion messages per month, enabling more than 30 million unique monthly Web and mobile users to exchange messages on the likes of Facebook Chat, MSN, Google Talk, Yahoo Messenger and ICQ.

The company also offers a service called eBuddy XMS, which is basically a free, real-time messaging app for smartphones that rivals WhatsApp and others.

eBuddy is privately held and earlier received financial backing from Prime Technology Ventures and Lowland Capital Partners.

Image credit: MAARTJE BLIJDENSTEIN for AFP / Getty Images