Protesters have hurled rubbish at the Beijing Olympic torch and brawled with Chinese supporters in a chaotic Japanese leg of the relay.
The event has left at least four people injured.
Thousands of Chinese students flocked to the mountain town of Nagano, turning the streets into a sea of red national flags.
Hundreds of demonstrators also came out in force, ranging from Tibet supporters to members of Japanese nationalist groups.
Some of the latter waved an old imperial flag and held up signs reading "Shame on China!"
"I support the Tibetans, Uighurs, Mongolians and Taiwanese who are against China. We support any group that's against Communist China," said Yasuhiro Yagi, a self-described Japanese right-wing activist.
Protesters threw rubbish, eggs and flares at the torch.
Furious Chinese supporters surrounded demonstrators who were waving Tibetan flags.
More than three thousand police were deployed along the route in Nagano which was the site of the 1998 Winter Olympics.