Japan's Yugo Kozaki beat Brazil's two-time world champion Douglas Brose to win gold on a good day for the next Summer Olympic host nation at the Karate 1-Series A event in Salzburg.
Kozaki, the 2015 world junior champion, triumphed in under-60 kilograms kumite final to booster his pedigree three years before a home Games in Tokyo.
Samdan Eray of Turkey shared bronze with Oleg Filipovych of Ukraine at at Sporthalle Alpenstraße in the Austrian city.
There was Japanese domination in the men's kata event as Ryo Kiyuna won gold.
Issei Shimbaba took silver while bronze medals were shared by Takuya Uemura and Arata Kinjo.
Ayumi Uekusa also claimed the spoils in the women's over-68kg kumite event.
She beat Eda Eltemur of Turkey in the final and another Turk, in Meltem Hocaoglu, shared bronze with France's Florentin Anne Laure.
Germany also claimed two gold medals.
Jonathan Horne beat France's Salim Bendiab to claim over-84kg men's kumite honours.
Third place finishes were secured by The Netherlands' Rob Timmermans and Serbia's Slobodan Bitevic.
Germany's women's kata team beat Turkey in the final as Serbia and Slovakia shared bronze.