Reigning world silver medalist Yasuhiro Koseki and Olympic bronze medalist Daiya Seto each collected their second gold medals on Wednesday as Japan won four events on the fourth day of Asian Games swimming.

Koseki, who won silver in the 200 breaststroke at the 2017 worlds, shook off a slow morning heat to win the men's 100-meter breaststroke gold from Lane 1 in a games-record 58.86 seconds, completing a 100-200 breaststroke double.

"I could not achieve the 58.50-second range that I was aiming for but I swam the first half of the race faster than at any time before," Koseki said after beating China's Yan Zibei by 0.45 and Rio Olympic gold medalist Dmitriy Balandin of Kazakhstan by 0.53 at GBK Aquatic Center in Jakarta.