Daiya Seto, a prominent Japanese swimmer, has been a significant figure in the sport since he began swimming at age five. Initially involved in both football and swimming, Seto found swimming more engaging. He currently represents CHARIS & Co in Japan and is coached by Takayuki Umehara and Takeshi Kato since 2022.

| Season | Event | Rank |
|---|---|---|
| 2021 | Men's 200m Individual Medley | 4 |
| 2021 | Men's 400m Individual Medley | 9 |
| 2021 | Men's 200m Butterfly | 11 |
| 2016 | Men's 400m Individual Medley | B Bronze |
| 2016 | Men's 200m Butterfly | 5 |
Seto has had a distinguished career with numerous accolades. He was named Asian Male Swimmer of the Year by SwimSwam in 2018 and 2019. Additionally, he received a Special Citation Award at the 2018 Japan Aquatics Awards and Excellence Awards in 2016 and 2018.
In 2013, Seto earned a Special Award at the Japan Sports Awards and an Excellence Award at the Japanese Olympic Committee Awards. His achievements also include an Honorary Prize at the 2014 Saitama Prefecture Sports Awards and the Moroyama Town Special Merit Award.
Seto made history by becoming the first swimmer representing Japan to defend a long course world title. He won the 400m individual medley at the 2013 World Championships in Barcelona and repeated this feat at the 2015 Championships in Kazan.
Seto faced several challenges throughout his career. He withdrew from the 200m individual medley at the 2019 National Short Course Championships due to a left knee injury. In September 2015, he underwent surgery on both heels but returned to competition by January 2016.
Seto cites his family as the most influential people in his career. He looks up to Japanese swimmer Kosuke Hagino as his idol. His hobbies include watching films, which he often shares on his Facebook page.
Seto's wife, Yuka Mabuchi, has represented Japan in diving. She won silver medals in women's synchronised 3m springboard and synchronised 10m platform at the 2012 Asian Championships in Dubai. Her father, Suei Mabuchi, is a diving coach who served as a coach for the Japanese national team at the Olympics in 2016 and 2020.
Looking ahead, Seto aims to win gold at the 2024 Olympic Games in Paris. Despite considering retirement after not winning a medal at the Tokyo 2020 Olympics, he decided to continue pursuing his dream of an Olympic gold medal.
"Retirement also crossed my mind," Seto said. "There have been times when I thought that it would be better for my family if I quit swimming and had a regular job. However, I still had a strong feeling that I wanted to continue and try again."
Daiya Seto remains committed to achieving his goals while balancing his personal life and professional responsibilities. His journey continues to inspire many aspiring athletes worldwide.
Daiya Seto, a prominent Japanese swimmer, has been a significant figure in the sport since he began swimming at age five. Initially involved in both football and swimming, Seto found swimming more engaging. He currently represents CHARIS & Co in Japan and is coached by Takayuki Umehara and Takeshi Kato since 2022.