Kuboi, 16, secured the first title of the event at the Croatian capital’s Dom Sportova Arena thanks to victory over Kazakhstan’s Abiba Abuzhakynova.

The reigning junior Asian champion prevailed courtesy of an osaekomi for 20 seconds.

Abuzhakynova tried everything to escape but Kuboi maintained a vice-like grip.

The first women’s under 44kg bronze medal was awarded to Belgium’s Lois Petit, who held down Uzbekistan’s Gulnur Muratbaeva with a sankaku-gatame.

The second was won by Russia’s Kristina Bulgakova at the expense of Brazil’s Laura Ferreira.

In the men’s under 60kg final, All-Japan Junior Championships winner Sugimoto defeated junior European champion Karamat Huseynov of Azerbaijan after 30 seconds of golden score.

Sugimoto, who was competing in his first IJF event, trapped Huseynov with a kesa-gatame hold for 20 seconds and secured the biggest victory of his career.

Mongolia’s Amarbold Jagvaraldorj beat Brazil’s Robson Penna to the first of the two bronze medals before Japan’s Genki Koga held off Russia’s Ayub Bliev to clinch the second.

Among today’s other winners was The Netherlands’ Amber Gersjes, who defeated Spain’s Laura Martinez Abelenda in the women’s under 48kg final.

An additional two-and-a-half minutes was required to separate the pair with a third and final shido against Martinez Abelenda gifting the gold medal to Gersjes.

It was a repeat of the outcome of last month's Junior European Championships final in Maribor in Slovenia.

Slovenia’s Marusa Stangar and Cuba’s Melissa Hurtado Munoz were the bronze medallists as Kazakhstan’s Akmaral Nauatbek and Russia’s Daria Pichkaleva just missed out on a podium place.

Also tasting victory today was Junior European Cup silver medallist Jaba Papinashvili of Georgia in the men’s under 55kg category.

Papinashvili had too much attacking threat for former junior European champion Natig Gurbanli, launching a series of committed movements that troubled his Azeri opponent.

The 19-year-old produced two waza-ari scores which went unanswered and concluded the scoring.

Kazakhstan's Bauyrzhan Narbayev won the first bronze medal match to the disappointment of compatriot Damir Bolatbekov.

He was joined of the third step of the podium by Mongolia’s Unubold Lkhagvajamts, who later overcame Georgia’s Vano Niniashvili.

Action in Zagreb is due to continue tomorrow when competition will be held in the men's under 66kg and under 73kg categories and women's under 52kg and under 57kg divisions.

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