Kosuke Hagino, a renowned Japanese swimmer, has had a remarkable career marked by numerous achievements and challenges. Born in Japan, Hagino began swimming at just six months old. His mother enrolled him in a baby swimming class to help him make new friends after the family moved to a new town.

| Season | Event | Rank |
|---|---|---|
| 2021 | Men's 200m Individual Medley | 6 |
| 2021 | Men's 4 x 200m Freestyle Relay | 12 |
| 2016 | Men's 400m Individual Medley | G Gold |
| 2016 | Men's 200m Individual Medley | S Silver |
| 2016 | Men's 4 x 200m Freestyle Relay | B Bronze |
| 2016 | Men's 200m Freestyle | 7 |
| 2012 | Men's 400m Individual Medley | B Bronze |
| 2012 | Men's 200m Individual Medley | 5 |
Hagino's career is decorated with numerous awards and honours. He was named Asian Male Swimmer of the Year at the 2020 Swammy Awards. He also received an Excellence Award at the 2018 and 2017 Japan Aquatics Awards and was named Swimmer of the Year at the 2016 Japan Aquatics Awards.
In 2014, Swimming World Magazine named him Male Swimmer of the Year. He was also honoured as the Most Valuable Player at the 2018 Asian Games in Indonesia by the Olympic Council of Asia. Additionally, he received the New Athlete Award at the 2012 JOC Sports Awards in Japan.
Hagino faced several challenges throughout his career. In July 2015, he fractured his right elbow after falling off a bicycle during a national training camp in Vichy, France. This injury prevented him from training for eight weeks and caused him to miss the 2015 World Championships in Kazan, Russia. He later underwent surgery on his right elbow in September 2016.
In early 2015, Hagino experienced pain in his right shoulder, which affected his performance. Despite these setbacks, he continued to excel in his sport.
In January 2018, Hagino was diagnosed with a life-threatening liver abnormality. He received three weeks of treatment in hospital before returning to competition in April 2018. Reflecting on this period, he said, "I was told, 'It's really bad and, if you carry on swimming with it, you'll die'."
In March 2019, Hagino took a three-month break from swimming due to depression. This break led him to miss that year's world championships in Gwangju, South Korea. He admitted that he had started to dislike swimming and even hated getting into the water during this time.
"Even if I was practising hard, I couldn't get the results I wanted in competitions and I experienced extreme depression," Hagino said. "Physically and mentally I went back to point zero."
In October 2021, Hagino announced his retirement from competitive swimming. He expressed his intention to undertake postgraduate studies starting in 2022. "I will take what sport has taught me into my future life," he stated.
Kosuke Hagino is married to Miwa, a Japanese singer-songwriter. The couple has one child together. His nickname is "The Rising Son," reflecting his prominence in Japanese swimming.
Hagino's sporting philosophy is simple yet profound: "Take care of your physical condition and do your best." His hero is US swimmer Michael Phelps, who has been an inspiration throughout his career.
Kosuke Hagino's journey through swimming has been one of dedication, resilience, and triumph over adversity. His story continues to inspire many young athletes around the world.
Kosuke Hagino, a renowned Japanese swimmer, has had a remarkable career marked by numerous achievements and challenges. Born in Japan, Hagino began swimming at just six months old. His mother enrolled him in a baby swimming class to help him make new friends after the family moved to a new town.