Japanese judokas won all four events on the second day of competition at the International Judo Federation (IJF) Osaka Grand Slam.
Masako Doi successfully defended her women's under-63 kilogram title in a competition dominated by Japanese athletes.
Doi boosted her Tokyo 2020 prospects by holding down compatriot Nana Kota for an ippon score.
The podium was completed by Nami Nabekura and Miku Tashiro, with the Japanese competitors overcoming Cuba's Maylin Del Toro Carvajal and South Korea's Han Hee-Ju.
A close women's under-70kg final saw Yoko Ono emerge as the winner of the competition.
Ono appeared to have beaten The Netherlands' Kim Polling with a waza-ari score, but a video review saw the decision reversed by officials.
A golden score period was required to separate the two, with Ono eventually securing a match-winning ippon.
Chizuru Arai added to Japan's medal collection by beating Venezuela's Elvismar Rodriguez in the first bronze-medal match, before Giovanna Scoccimarro defeated fellow German Miriam Butkereit.
Masashi Ebinuma emerged as the winner of an all-Japanese men's under-73kg final against Soichi Hashimoto, with the clash seeing two former world champions go head-to-head.
A slip from Hashimoto would prove crucial, with Ebinuma able to hold his compatriot to secure an ippon.
Mongolia's Odbayar Ganbaatar secured the first bronze medal in the division by overcoming Japan's Kenshi Harada.
Tajikistan's Somon Makhmadbekov also overcame Japanese opposition in his bronze-medal match, as he beat Arata Tatsukawa.
Japan's Takanori Nagase boosted his prospects of representing the host nation in the men's 81kg event at Tokyo 2020.
Nagase secured a key victory over team mate Sotaro Fujiwara as the battle for Japan's Olympic place continued.
Russia's Turpal Tepkaev and the Netherlands' Frank De Wit completed the podium, courtesy of winning their bronze-medal bouts against Uzbekistan's Kamoliddin Rasulov and Japan's Hikaru Tomokiyo.
Competition continues tomorrow with the final five medal events.
Watch all the action on Judo TV.