The 19-year-old retains her world title as hosts clinch their first gold medals in Tokyo.
Japanese judoka Uta Abe has secured her second-consecutive world title.
The 19-year-old beat Russia's Natalia Kuziutina with an ippon after just 29 seconds of the 2019 judo world championships women's -52kg final.
"I'm very pleased to have defended the world title in Tokyo," the Tokyo 2020 poster girl told reporters after the win.
"It's a different kind of joy compared to last year. I was a little unsure.
"I had the crowd behind me and their support was huge. They were the main reason I was able to fight the way I did today.
"Tokyo Olympics is next and it's the only thing on my mind now. I really hope I can win now".
In the previous round, Abe overcame Olympic champion Majlinda Kelmendi in an epic match.
The highly-regarded pair were competing against one another for the first time, and fittingly the bout went to the golden score.
Abe eventually prevailed with a well-executed hold down.
"I was determined to beat [Kelmendi] no matter what," the Japanese said afterwards.
"It went into extra time and I was absolutely spent and I nearly gave in, but I didn't give up till the finish. I was having a hard time finishing my moves but I managed to do it in the end with my favourite technique."
The Kobe-born fighter started off her campaign with a win over Pan American Games champion Larissa Pimenta of Brazil, before dispatching Uzbekistan's Diyora Keldiyorova and Brit Chelsie Giles.
Kelmendi went on to beat Joana Ramos for a bronze medal, while Japanese third seed Ai Shishime also took a bronze following a win over Amandine Buchard of France.
Joshiro Maruyama clinched Japan's second gold medal of the night.
The men's -66kg second seed defeated Kim Lim-hwan to claim his maiden IJF world title.
"I had to go through a lot to get to this point. It means a lot," Maruyama said.
"It probably took longer than a lot of champions to get here, but my ultimate goal is to win a gold medal at the Tokyo Olympics" - Joshiro Maruyama
"This win is massive for me and I hope I can build on this for the future."
The 26-year-old previously beat reigning double world champion Hifumi Abe in an all-Japanese semi-final.
On his way to gold the Miyazak native beat beat Czech Republic's Pavel Petrikov, Slovenia's Adrian Gomboc and Uzbekistan's Sardor Nurillaev.
Korea's Kim, ranked No. 29 in the world, caused the surprise of the day by eliminating Georgian top seed Vazha Margvelashvili in the third round.
Moldova’s Denis Vieru claimed one of the two bronze medals on offer, following a win over Baskhuu Yondonperenlei of Mongolia.
Abe also took bronze by beating Manuel Lombardo of Italy.