Hifumi Abe is a dominant force in judo, unbeaten in the U66kg division since 2016.
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His 17-year-old sister Uta has been no less imperious, despite the fact she is still a high school student.
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In February 2017, Uta became the youngest ever winner on the IJF World Tour, taking gold in the Dusseldorf Grand Slam aged 16.
IJF / Gabriela Sabau
She's still never lost a match outside of her native Japan.
IJF / Gabriela Sabau
After missing out on selection from the Rio 2016 Olympics as a teenager, Hifumi has become one of the sport's leading fighters, winning the World Championships at his first attempt in Budapest.
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Both have earned reputations for their explosive and dynamic fighting style on the mat.
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"Something I keep in mind is to never back down -- to always move forward and keep attacking," Uta told CNN Sport.
IJF / Gabriela Sabau
The brother and sister celebrated a unique feat at the Tokyo Grand Slam in December 2017 when they both came away with the spoils.
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The two Abes are looking to maintain their dominance between now and their home Olympics in Tokyo in 2020.
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Hifumi has no doubt of his ability to shine in front of his home crowd, saying of the Olympics, "I will win."
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Modest and self-effacing off the mat, Uta is no less confident about her abilities on it. "My short-term goal is to win the World Championships in Baku later this year," she told CNN. "My mid-term objective is to win the Olympic gold medal at Tokyo 2020."