TOKYO — Daisuke Hayakawa is the coach of Japan’s Olympic skateboarding team, which is likely to dominate the sport when it makes its debut at this summer’s Olympics in Tokyo. But that does not mean he would dare set his skateboard down on a city sidewalk.

He may be a rebel in Japan, but he has manners.

“Skateboarding became one of the sports at the Olympics, but the image of skateboarding in Japan is that it’s an activity for unruly kids,” he said.

So as evening fell on a warm summer day last year, Hayakawa, 45, carried his board in the crook of his wrist. He left home in central Tokyo and took the subway to Kanegafuchi Station, a half-hour train ride north of downtown, and walked about 15 minutes toward the Sumida River.

The streets and sidewalks were mostly empty. Yet his skateboard still never touched the ground.