Takamasa Anai won the men's 100-kg title at a Grand Prix meet in Hamburg on Sunday when Beijing Olympic bronze medalist Henk Grol of the Netherlands withdrew from the final because of an injury.
In the all-Japanese 70-kg women's final, Mina Watanabe deployed a sleeve-lifting hip throw to topple Asuka Oka to the mat for an ippon victory 2 minutes, 41 seconds into the match.
Anai claimed his second title following his Grand Slam Paris victory two weeks ago.
In the semifinal, Anai avenged his third-round defeat to Daniel Brata at the World Cup Vienna meet a year ago by scoring "waza-ari" and then pinning the Romanian.
"I try to do well in both standing and groundwork, so I'm glad I finished him off like that," the 24-year-old said. "But I wanted to fight in the final, so I'm a little dissatisfied."
Yasuyuki Muneta finished third in the men's over 100-kg category, won by Abdullo Tangriev of Uzbekistan.
A total of five Japanese judoka claimed titles after two days of competition.