Ilia Malinin led all the way to take the title with a winning margin of 22.73 points over Japanese rival Yuma Kagiyama after the free skate.
Team Japan was nearly flawless on Sunday at the Milano Cortina Olympics, but Ilia Malinin had the last word.
Japan will have to contend with a resurgent United States in Milano-Cortina, as well as Russian skaters for the first time since the Beijing Olympics.
World champion Alysa Liu made it an American double in Nagoya, coming from behind to win the women's competition.
Chiba, 19, skating to Donna Summer's 'Last Dance,' scored 70.86 to edge 0.02 points ahead of Amber Glenn of the United States.
Kagiyama made an error early in the free skating but his expressive, lightning-quick performance still earned him 200.76 points for a total of 307.58.
Shun continues technical excellency, well done. but Libertango, seriously?
and while no colour, good to see that his costume designer remembered sparkles.
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