Nuro, the Silicon Valley-based startup backed by Nvidia, Uber, and SoftBank, is testing its autonomous vehicle technology in Japan.

Toyota Prius vehicles equipped with Nuro’s self-driving software — and human safety operators behind the wheel as backup — began testing on public roads in Tokyo last month. The testing marks the first overseas expansion for the startup, which upended its business model two years ago.

Nuro said testing in Japan introduces a number of new challenges and different driving styles and rules. For instance, vehicles drive on the left side of the road, and Tokyo’s streets have dense traffic.