Soichi Hashimoto won the men's 73-kg gold medal at the world championships on Wednesday, when fellow worlds debutant Tsukasa Yoshida settled for silver.
In his final, Hashimoto defeated Azerbaijan's Rustam Orujov, the silver medalist at last year's Rio de Janeiro Olympics. Japan has now won five gold medals from the six weight-class competitions held through the first three days of the event.
Yoshida, ranked second in the world, fell in the women's 57-kg final to Rio silver medalist and world No. 1 Sumiya Dorjsuren of Mongolia, who clinched the extra-time victory on a decision by the judges.
"I was not in the best form, I entered the match determined to win. But my weaknesses were exposed (in extra time)," Yoshida said.
The 21-year-old Yoshida advanced to the final after an ippon victory over world No. 3 Helene Receveaux of France.
Hashimoto, the top-ranked judoka in his division, defeated Georgia's Lasha Shavdatsuashvili, a Rio Olympics bronze medalist in this division and the 2012 Olympic 66-kg champion, on shido penalties.
The 26-year-old Hashimoto then won his semifinal against Azerbaijan's Hidayat Heydarov, the 2017 European champion, by ippon.