The "Abes."Two explosive young athletes who are taking the sport of judo by storm and look set for greatness as the Tokyo 2020 Olympic Games appear on the horizon.Hifumi and Uta Abe, 20 and 17 respectively, both took gold medals at the Tokyo Grand Slam on Saturday, whetting the appetite of fans who hope to see both competitors on top of podiums again in the future.READ: Inside the Kodokan — judo's spiritual homeJapanese dominance is the the norm in judo and the opening day of this two-day event was no different. The hosts claimed all seven gold medals on offer, with four of the finals contested between two Japanese judokas.In total, the hosts won 22 of the 29 medals available on Saturday.But it was the Abe siblings who stole the show, with Uta cast in the headline role.She cemented her reputation as the sport's wonderkid, adding a first grand slam triumph in the -52kg category to the junior world title she picked up earlier this year.Uta delivered a crushing victory over compatriot Rina Tatsukawa with an ippon seoi-nage after just 45 seconds of the contest."I am very, very happy to have won this Tokyo Grand Slam," she said after collecting her medal. "This was my main target for the year, and with it being one of the last events of 2017, it's a great way to end the year."READ: Life through a lens with a judo photographerUta became the youngest ever winner of a grand prix event in February, coming out on top in Dusseldorf while she was still in high school.And her exploits spurred on her older brother, who came into the weekend as a world champion in the -66kg category and lived up to his billing."I saw my sister win her final before I fought. Her victory meant I was even more motivated to win gold," he said after a hard-fought win over Joshiro Murayama in the final.Hifumi has now won his last 28 matches, although his admiration for his prodigious younger sister is clear."If she had won and I hadn't, then even though I'm the older brother, it would have been me looking up to her," he said.The Abe siblings boast rich judo heritage. Their uncle is Tadahiro Nomura, who won three consecutive Olympic gold medals in the -60kg category between 1996 and was crowned world champion in 1997.READ: Japanese judo icon Kosei InoueGlobal success is demanded in Japanese judo. The fans who watched on from their seats inside the arena had their loyalties split between the country's numerous elite-level judokas.Bands of spectators displayed their allegiances by wearing the colors of their home judo clubs, with some bunched together in groups of up to 200.And when their favored competitor took to the tatami, they screamed their names with increasing vigor as the day wore on.But the crowd was denied the one bout they had all come to see.Soichi Hashimoto is the reigning -73kg world champion and one of the most talented judokas on the planet.He has made the division his own over the last 12 months, winning the Tokyo Grand Slam in 2016.Fans were anxious to see how he would fare against the returning Shohei Ono, a two-time -73kg world champion who took time out of the sport to concentrate on his studies after winning the Olympic title in 2016.Ono was selected for the Rio Games ahead of Hashimoto and a first showdown between the two was set to be the headline act of this grand slam weekend.But it wasn't to be. Ono, dubbed the "thrower of throwers", was forced to withdraw from the competition with a knee injury ahead of his second match, while Hashimoto was forced to settle for a bronze medal.It was an anticlimactic end to the event for both athletes, with Ono in particular cutting a dejected figure in the stands."I realized that this is my ability, this was the best I can do today," said the 25-year-old Ono. "I am starting from zero."Japanese men's head coach Kosei Inoue was unconcerned by Ono's withdrawal, saying its more important for him to be in peak condition ahead of major competitions such as the 2019 World Championships, which will be staged in Tokyo."He made the correct judgment in pulling out," said Inoue, himself a three-time world champion and an Olympic gold medalist in 2000."He doesn't need to peak right now. I want Ono to be in top shape and awe the judo world when I matters."