The women's competition, which is also sanctioned by the World Snowboard Tour, was held on the final jump in the Big Bucks Park. The eight finalists each had three runs and the combined total of their two top scores determined the placings.
Competitors have been challenged by the weather; fog and wind have caused delays to the schedule all week.
However, when competition finally got under way in the afternoon, the youngest competitor in the field, Murase, seemed to be taking it all in her stride.
She put down a frontside 720 melon grab for a score of 88.20 on run one and then wrapped up the win with a backside 720 mute grab for a score of 92.80 on run two.
Even with the gold medal already in the bag, the gutsy teenager had planned to step up with a frontside 900 on her last jump but sketched the landing.
''I'm really stoked to win today. I'm looking forward to coming back next year and winning again,'' Murase said.
''I'm a bit disappointed I didn't stomp the front nine on my third jump so I'm going to be more careful with that next time.''
Canada's Sommer Gendron claimed the silver medal, recovering from a crash on run one to land a backside 360 mute on run two and a cab 540 on run three.
Ziyan Ren (China) finished in the bronze medal position, with a frontside 360 indy on run one and backside 180 on run two.
The FIS Junior Freeski Slopestyle World Championship 2018 qualifiers scheduled for yesterday were postponed due to poor visibility.
