According to Techcrunch, the round was led by Eight Road Ventures with participation from other investors including Mirai Creation Investment Limited Partnership and Golden Asia Fund II.

Founded four years ago in Tokyo, Whill is now headquartered in San Francisco. It has raised a total of $30.2 million in venture funding to date. Some of Whill's Series B will also be used to market its devices in the United States, where it launched an airport rental program last month.

Whill recently received approval from the Food and Drug Administration for the Model M, which is meant to be a more attractive and navigable alternative to motorized wheelchairs. This means it can now be marketed as a medical device in the U.S. and doctors will be able to begin writing prescriptions for it this summer.

The Whill's products -- including the Model M and its predecessor, the Model A -- use a patented wheel that allows users to make tight turns even on rough terrain and sloping surfaces. Other features that Whill hopes will allow it to stand out from competitors (like the iBot, which Toyota and Segway inventor Dean Kamen recently announced plans to bring back) include technology that will allow devices to drive autonomously and be managed remotely.