It proved a superb boost for Asian Paralympic sport in a competition doubling as a test event for Pyeongchang 2018.

Narita, competing in his first season in the sport, placed sixth in his first run before moving up the leaderboard.

His final time of 41.62sec proved enough to beat the Finnish world champion by 0.29 seconds.

United States' Mike Shea clinched third place in 42.02.

"I was really surprised," Narita, a World Championship bronze medallist, said.

"Still Matti is really strong. 

"He is so strong, so fast, faster than me.

"But I got first place and am very happy."

Suur Hamari still managed to to take the overall title.

There was American success in the SB-UL category as overall champion Mike Minor beat France's Maxime Montaggioni.

His time of 42.42 proved enough for gold by 1.60 seconds as Italian Manuel Pozzerle clocked 44.05 for the bronze medal.

Dutchman Chris Vos took the SB-LL1 spoils with a final-run time of 44.33, despite a fall in the second run,

It was 0.80 seconds faster than Croatia’s Bruno Bosnjak, who clinched first career podium finish.

American Mike Schultz took third place in 45.53.

Reigning world champion Brenna Huckaby claimed a US win in the women's SB-LL1 class by nearly two seconds in front of France's overall World Cup winner Cecile Hernandez-Cervellon.

Huckaby clocked 45.58 in comparison with 47.57 for Hernandez-Cervellon.

Amy Purdy joined her winning team-mate on the podium, taking bronze in 48.30.

Dutch superstar and Paralympic champion Bibian Mentel-Spee gained a predictable SB-LL2 victory in 45.58.

Australia’s Joany Badenhorst came close to reaching Mentel-Spee’s speed in the second run but left with second place in 46.46. 

Dutch rider and overall World Cup and banked slalom title winner Lisa Bunschoten finished third in 46.74.