Kuwabara had reached the final by beating European champion Islam Yashuev of Russia at Centro Internacional de Convenções do Brasil.

The 27-year-old then followed up by securing a sensational first Grand Slam title by throwing his Brazilian compatriot with ippon to claim a maiden Grand Slam title of his career.

Yashuev defeated Spaniard Rodrigo Costa Lopes to earn the bronze medal alongside Francisco Garrigos of Spain.

Garrigos overcame Brazilian Renan Torres with a waza-ari score after 82 seconds of added time to claim bronze.

A second Brazilian victory came in the men's under-66kg as Daniel Cargnin won his first IJF World Judo Tour event.

Cargnin defeated Italy's Manuel Lombardo with a single waza-ari score as Willian Lima of Brazil and Frenchman Kilian Le Blouch took bronze medals with victories against Russian Abdula Abdulzhalilov and Sebastian Seidl of Germany.

As the women's competition began, Montreal Grand Prix silver medallist Catarina Costa of Portugal denied Brazil a dream start.

She defeated Gabriela Chibana to win the under-48kg gold with a sode-tsurikomi-goshi move.

Waza-ari scores in their respective bouts saw Shira Rishony of Israel and Spain's Laura Martinez Abelenda seal bronze medals against German Katharina Menz and Éva Csernoviczki of Hungary.

Rio 2016 silver medallist Odette Giuffrida of Italy claimed under-52kg gold against Brazilian Larissa Pimenta.

The bronze medals went to Eleudis Valentim of Brazil and Japan's Natsumi Tsunoda.

They defeated Cancun Grand Prix bronze medallist Joana Ramos of Portugal and world number 13 Agata Perenc from Poland respectively.

Two-time world medallist Nekoda Smythe-Davis clinched a second Grand Slam gold of her career in the under-57kg contest.

The Briton won the Düsseldorf Grand Slam in 2018 and sealed a second Slam title with an o-soto-gari for ippon after two minutes of additional time against Brazilian Ketelyn Nascimento.

Germany's Theresa Stoll lost her semi-final to Smythe-Davis in the eighth minute of added time but made amends against Sarah Leonie Cysique of France to earn bronze.

The other bronze medal was won by Rafaela Silva of Brazil, who saw off European Games bronze medallist Telma Monteiro of Portugal. 

Silva famously won the Olympic gold medal at Rio 2016 but is now facing a two-year drugs ban after testing positive at the Pan American Games for asthma drug fenoterol and being stripped of her title. 

The IJF Grand Slam is due to continue tomorrow with the men's under-73kg and under-81kg and women's under-63kg and under-70kg contests.

Watch all the action on Judo TV.