TOKYO (Kyodo) -- Kenya Kohara upset reigning Olympic champion Takanori Nagase to claim the men's 81-kilogram gold medal in one of several all-Japanese finals Saturday at the International Judo Federation's Grand Slam Tokyo.
Kohara's surprise victory headlined a dominant opening day for the host nation at the Tokyo Metropolitan Gymnasium.
The 28-year-old overcame another compatriot, Sotaro Fujiwara, to advance to the final against multiple Grand Slam champion Nagase, who won gold at last year's Tokyo Games.
World championship runner-up Haruka Funakubo topped the women's 57-kg podium by beating Tokyo Olympic bronze medalist Tsukasa Yoshida.
Tokyo Olympian Miku Takaichi won the women's 63-kg with a victory over Seiko Watanabe, who defeated reigning world champion Megumi Horikawa in the semis.
Asian Games champion Saki Niizoe beat Australia's Aoife Coughlan to secure the women's 70-kg gold for Japan.
Kosuke Mashiyama won the men's 90-kg by defeating Germany's Eduard Trippel after downing Tokyo Olympic gold medalist Lasha Bekauri of Georgia, while multiple Grand Slam winner Soichi Hashimoto added another men's 73-kg title with a victory over compatriot Hayato Koga.