Daiya Seto captured the men's 400 meters individual medley on the final day of the Mare Nostrum series in Monaco on Sunday.
Seto clocked 4 minutes, 10.58 seconds, outpacing Hungary's David Verraszto, who took silver in 4:11.28. Seto's Japanese teammate Kosuke Hagino took the bronze in 4:13.05.
Elsewhere for Japan, Yasuhiro Koseki won the men's 100 breaststroke in a meet record time of 59.93, while former Olympic champion Kosuke Kitajima could only manage eighth.
Ryosuke Irie led Japan to a 1-2 finish in the men's 200 backstroke logging 1:55.36, winning the event ahead of Masaki Kaneko who marked 1:58.18.
In women's action, Kanako Watanabe won the 200 individual medley in meet record time of 2:09.95 and also placed second in the 200 breaststroke.
Natsumi Hoshi won the 200 butterfly in 2:08.25, followed by compatriot Sakiko Shimizu in second.