Kosuke Hagino outraced defending world champion Daiya Seto in the men's 400-meter individual medley final on the first day of the 90th Japan national championships at Tokyo Tatsumi International Swimming Center on Thursday.

Seto, who won the gold medal in the event at last year's world championships in Barcelona, Spain, closely followed Hagino for the first 100 meters. But Hagino widened the lead over fellow 19-year-old swimmer during the backstroke portion of the race afterward, and wound up posting an easy win with a time of 4 minutes, 7.88 seconds. Seto took second in 4:12.30.

Hagino had a legitimate chance to break his own national record, but fell 0.27 seconds short. He appeared to run out of the gas over the final 25 meters or so.