Americans Kaitlin Hawayek and Jean-Luc Baker replaced the overnight leaders from Russia to take gold in the ice dance event at the International Skating Union Grand Prix of Figure Skating leg in Hiroshima.
The American pair were ranked second after the rhythm dance section of the competition behind Russians Tiffani Zagorski and Jonathan Guerreiro, but managed to score enough in their free skate to take the victory.
The 2018 Four Continents champions added the NHK Trophy to their achievements after dancing to "Trampoline Theme" and "In This Shirt" by The Irrepressibles in the Hiroshima Prefectural Sports Centre.
"Our main goal was really to try to put out two solid performances, but also to understand our programmes," Baker said.
"It is our first event.
"We really just wanted to get our feet wet.
"We're very happy that we're walking away with the gold medal."
The overnight leaders slipped to second after only being ranked fourth best in the free dance.
Zagorski and Guerreiro's total of 183.05 points was not enough to challenge the Americans' total of 184.63.
Rachel and Michael Parsons secured the US a second medal in the event, finishing third on 178.64 points.
As the competition closed, hosts Japan celebrated winning both individual titles as the US and Russia took the plaudits in the ice dance and pairs events respectively.
The ISU Grand Prix of Figure Skating continues with the Rostelecom Cup as the series heads to Moscow, Russia, next weekend.
Following the Moscow Grand Prix, the skaters have the opportunity to compete in Grenoble, France.
These events will provide the athletes with the last qualification opportunities for the ISU Grand Prix of Figure Skating Final in Vancouver, Canada in December.