Takanori Nagase won the gold medal in the men's 81-kg division at the Zagreb Grand Prix on Saturday, the second day of the three-day judo competition in the Croatian capital.
Nagase, a former world champion and bronze medalist at the 2016 Rio Olympics, scored an ippon victory over Canadian judoka and London Olympic bronze medalist Antoine Valois-Fortier in the final at Dom Sportova.
It was his second Grand Prix title in July, after the 25-year-old Nagasaki Prefecture native captured gold at the Montreal Grand Prix earlier this month.
"It boosts my confidence even more to be able to win back-to-back Grand Prix titles," Nagase said.
"If I keep executing on chances, I'll be within reach of the Tokyo Olympics."
In the women's 63-kg final, Nami Nabekura settled for silver after she was penalized with a third shido in added time, allowing Olympic champion Tina Trstenjak of Slovenia to take home the gold.
Japan is at the top of the medal standings with two golds and two silvers so far.