Despite officials carrying posters asking fans not to gather along the race course, many turned out for a chance to watch international athletes ride past.
"I got a day off at my company and came here to see if I'm able to have a glimpse of the competition somewhere," said Hisashi Onitsuka.
"We're outdoors so it won't get overcrowded. I think the risk of getting infected is extremely low, almost equal to zero," said Masao Kitada.
The race started early on Monday to make the most out of the morning's relatively cool temperatures.
The women's race takes place on Tuesday.