Teenager Akira Sone won her first women's heavyweight gold medal at the judo world championships on Saturday, where defending men's heavyweight champion Hisayoshi Harasawa lost to his 2016 Olympic nemesis.

The 19-year-old Sone, a gold medalist last year in the mixed team event, won when 29-year-old former Olympic champion Idalys Ortiz lost on penalties in the final of the women's over-78 kilogram division.

"She's such an amazing athlete, so any way I could beat her is a victory," said Sone, who was competing as an individual at the worlds for the first time and is aiming to return to the same venue next summer for the Olympics.

"My feeling is that I am going to make it to the Tokyo Olympics and win a medal without fail. I want to give my all until then so I can make that happen."

On the seventh day of competition at Tokyo's Nippon Budokan, Japan's defending world champion, Sarah Asahina, won her bronze medal match against Brazil's Maria Suelen Aletheman by ippon. Last year, Asahina defeated two-time world champion Ortiz in the final.

"Since my goal was to win a second-straight championship, the biggest emotion I'm feeling now is one of frustration," Asahina said. "Still, I was able at least to win a medal, and that's the bare minimum for me."

Japan's other 2018 champion fared only slightly better. Harasawa, 27, a two-time mixed team world gold medalist and silver medalist from the Rio de Janeiro Olympics, lost again to Rio champion Lukas Krpalek of the Czech Republic on penalties.

After seven days, Japan has four gold medals, two from the men and two from the women.