Yusei Ogawa, the son of an Olympic silver medalist judoka, won his first Grand Slam Tokyo championship in the over-100 kg division on Sunday.
On the final day of competition at Tokyo Metropolitan Gymnasium, Ogawa, whose father Naoya won a silver medal at the 1992 Barcelona Olympics, defeated defending Olympic champion Lukas Krpalek of the Czech Republic in the final.
After outlasting his opponent in a grueling 14-minute, 1-second match, Yusei Ogawa pumped his fist in celebration.
"I wasn't going to give in," he said after winning with his father watching on.
Naoya Ogawa said of his son, "His willpower carried him. Speaking as a father, that is the most important thing."
Two of the women's finals involved all-Japanese finals. Sara Asahina defeated Akira Sone to win her second-straight, over-78 kg championship. In the 70 kg final, Yoko Ono beat world champion Chizuru Arai to win her first Tokyo crown.
Shori Hamada captured the women's 78 kg title, while Rui Sato, who represented Japan at the worlds in the division, was third.
In the men's 90 kg, Kenta Nagasawa won the final over Yusuke Kobayashi.