Bike sharing has a lot going for it. It's mass transit that's ultracheap, burns body fat instead of fossil fuels and is adored by venture capitalists. But the business model has hit a major snag: parking.

Stringent laws against sidewalk clutter — and cultural sensibilities that are easily offended — make the problem more acute in Japanese cities than in places like Munich or Melbourne, where bicycles are piling up outside subway stations or turning up under bridges, sometimes to the dismay of neighbors and city officials.

Bike sharing took China by storm in 2016, quickly becoming a novel tech export, and is now facing a backlash even in environmentally friendly places where you'd expect it to be embraced. That's why the industry's biggest players are treading lightly in Japan, a country where free-form bicycle parking is outlawed and authorities routinely haul away bikes even if it means snipping locks.