Zan Kosir completed a dream two days in Asahikawa, the overall FIS Snowboard World Cup leader winning the parallel slalom event on Sunday.
The Slovenian was too good for American Justin Reiter in the final, with Mirko Felicetti taking third in Japan.
Fresh from winning the parallel giant slalom on Saturday, Kosir made it back-to-back victories.
The 30-year-old is well clear atop the parallel slalom standings with 2800 points, ahead of Roland Fischnaller (1580).
In the women's event, Julie Zogg claimed victory over Sabine Schoeffmann in the final after being runner-up a day earlier.
Julia Dujmovits, who beat Zogg on Saturday, was third.
Schoeffmann (1890 points) is ahead of Zogg (1750) in the parallel slalom standings.