Ryunosuke Haga, a prominent Japanese judoka, began his journey in the sport at the tender age of five in Saitama, Japan. Encouraged by his father, who later became his coach, Haga developed a passion for judo early on. His father, Yoshio Haga, was also a judoka and competed for Asahi Kasei in Japan.

| Season | Event | Rank |
|---|---|---|
| 2016 | Men's 100kg | B Bronze |
Ryunosuke Haga represents Asahi Kasei in Japan. He trains under the guidance of Yuya Yoshida at the club level and Kosei Inoue at the national level. Inoue is not just his coach but also his idol, as Haga has often expressed admiration for him.
Haga's career has seen its share of injuries. He first underwent surgery on his left shoulder in 2012. He injured it again during the 2017 World Championships in Budapest and had another operation in March 2018. He made a comeback at the 2018 Kodokan Cup All Japan Championships.
In 2016, Haga suffered a left knee injury that kept him out of the All Japan Championships. He required two months of rehabilitation before returning to competition.
Haga's achievements have been recognised with several awards. In 2016, he received the Kanagawa Sports Award, the Nabeoka Citizen Honorary Award, and the Miyazaki Prefecture Citizen Special Honorary Award. These accolades highlight his contributions to judo and his standing in Japanese sports.
Outside of judo, Haga balances his life as an athlete and an office worker. He is married and has one daughter born in 2019. He enjoys studying English in his free time, showcasing his interest in broadening his horizons beyond sports.
Haga lives by the motto "Be thankful." This simple yet profound philosophy reflects his gratitude towards those who have supported him throughout his career.
In addition to his sporting achievements, Haga has served as a member of the All Japan Judo Federation Athlete's Committee. This role allows him to contribute to the development of judo in Japan.
As of July 2024, Ryunosuke Haga continues to be an influential figure in judo. His journey from a young boy inspired by his father to a celebrated athlete is a testament to dedication and resilience.
Ryunosuke Haga, a prominent Japanese judoka, began his journey in the sport at the tender age of five in Saitama, Japan. Encouraged by his father, who later became his coach, Haga developed a passion for judo early on. His father, Yoshio Haga, was also a judoka and competed for Asahi Kasei in Japan.