In 2012, Kohei competed at the 2012 Short Course World championships. He finished ninth overall, with a time of 14:43.98, being eliminated in the semi-finals.
In 2013, Kohei competed in the 2013 Summer Universiade. He swam in the 400 meter freestyle, and placed second and won the silver medal in that event, with a time of 3:49.03, 4-tenths of a second behind 1st place finisher Ryan Napoleon, who had a time of 3:48.96.[1] He competed in the men's 1500 meter freestyle, also placing second, with a time of 15:00.15. His time was three seconds slower than first place finisher Sean Ryan.[2] Kohei won the gold medal in the 800 meter freestyle, with a time of 7:49.96, two seconds faster than 2nd place finisher, Sergii Frolov.[3] He later represented Japan in the 4x200 meter relay. Japan finished fourth.
At the 2014 Japan Open, Kohei set a national record in the 1500 meter freestyle, clocking 14 minutes and 54.80 seconds.[4]
Kohei competed at the 2014 Pan Pacific Championships. He swam in the 800 meter freestyle, placing sixth with a time of 7:54.07.[5] He also finished 6th in the 1500 meter freestyle, with a time of 14:57.71.[5]
At the 2014 Asian Games, Kohei placed fourth in the 400 meter freestyle, with a time of 3:51.09. Later, he went on to win the silver medal in the 1500 meter freestyle, with a time of 14:54.86, five seconds slower than 1st place finisher Sun Yang.[6]
Kohei competed at the 2014 Short Course World championships. He swam in the 1500 meter freestyle, and placed 12th overall with a time of 14:42.55.
Kohei competed at the 2015 Summer Universiade. He swam in the 1500 meter and 800 meter freestyle. In the 800 meter freestyle, he placed eighth with a time of 8:03.69. He later swam in the 1500 meter freestyle, winning the bronze medal with a time of 15:03.99.[7]
At the Japan Olympic trials, Kohei failed to qualify for the 2016 Summer Olympics, although he finished 1st in the 1500 meter freestyle. He had a time of 14:57.12, but couldn't qualify because the requirement to qualify for the Olympics was 14:55.30.[8]
Japan
