The Singapore-based startup is the sister-brand of existing short-term rental service PandaBed and has been gradually building up a network of properties in its home city since 2014.
It is solely focused on providing rental condos and living spaces for business travellers needing accommodation for a month or more.
The founders, Lester Kang and James Chua, launched PandaBeds two years before.
The investment in MetroResidences will be used to push the service into Hong Kong and Tokyo.
The Series A follows a seed round of $1 million in January lat year and an angel investment at launch.
Rakuten, which has its own sizeable Rakuten Travel consumer-facing brand, has previously invested in Cabify and bought tours and activities startup Voyagin in July 2015.