Ryu Shichinohe vanquished Daiki Kamikawa in the men's over 100-kg final to defend the title at the All Japan invitational weight class championships on Sunday.
The 24-year-old Shichinohe, an Okinawa native whose mother hails from Belgium and father is Japanese, defeated Kamikawa by ippon after scoring two waza-ari at Fukuoka Kokusai Center to claim bragging rights in the men's heaviest class.
"I wasn't able to win the title at the national championship (last month), so I wasn't in a position to talk about competing in the world championships," said Shichinohe. "I had to win today. I've been up and down with winning and losing but I want to continue to do my best to win consistently."
Takashi Ono became the first to win titles in three weight categories, capturing the men's 100-kg crown to add to the 81-kg class he won in 2005 and 2008 and his victory at 90 kg in 2010.
Hirotaka Kato, meanwhile, successfully defended the men's 90-kg title while Goki Maruyama emerged the winner at 81 kg.
Akari Ogata, who won the national championship last month, was stunned in a final loss to 21-year-old Ruika Sato in the women's 78-kg category.
Nodoka Shiraishi and Karen Nunira, whose father is Ghanaian and mother Japanese, both won their inaugural titles at over 78 kg and 70 kg, respectively.
The tournament doubled as the final qualifier for this summer's world judo championships in Rio de Janeiro.