Katinka Hosszu (HUN) added a further three wins to take her World Cup Victory tally to 33 on the first day of action at the Tokyo round of the World Cup.
She followed up an 8:24.89 win in the 800m freestyle with a 1:54.96 victory in the 200m freestyle and a 2:07.51 effort in the 200m medley for the triple.
Teammate Zsuzsanna Jakabos joined Hosszu on the podium twice: in the 200m free, she clocked 1:55.36, and in the 200m medley 2:07.92 for third place, Britain's Sophie Allen splitting the Hungarians on 2:07.85.
In other action, Daiya Seto (JPN) shaved a fraction off his own world cup record in the 400m medley, on 4:00.02. Japan also celebrated wins for Kazuya Kaneda, on 1:51.08 in the 200m butterfly, and Akihiro Yamaguchi, on 2:04.64 in the 200m breaststroke.
Yamaguchi is better than multiple Olympic champion Kosuke Kitajima was at 18, his national coach told reporters. Having missed the Olympic cut for London 2012, Yamaguchi, shaved 0.27sec off Olympic champion Daniel Gyurta's world 200m breaststroke record to leave the mark at 2:07.01 at a low-key meet in Gifu in September. Low-key is significant. The next trick for Yamaguchi is to do it when the heat is on.
"(Yamaguchi) is better than Kitajima was at his age," Japan's national coach Norimasa Hirai told local media in Tokyo. "But right now he doesn't have much of anything."
tell that to the fans: Yamaguchi has become something of a celebrity at home, crowds flooding to his local pool on Kagoshima island and disrupting his training, reports suggest.
"There has been a sharp rise in the number of people using the pool after I broke the world record," Yamaguchi said. "I haven't been able to find my top speed and my form is still not where it should be. I don't have that explosiveness."
Hirai has warned Yamaguchi to keep his feet on the ground.
"It's what happens when you break the world record and then spend a bit of time back home," said Hirai, who coached Kitajima to Olympic glory. "If you take your foot off just a little, you'll be nothing but a flash in the pan."
Yamaguchi, headed for the World short-course championships in Istanbul next month, said: "I might not be in top form just now but hopefully I can make up for it with my technique. I think I have a chance to break more world records."
Meanwhile, in Tokyo, the USA enjoyed victories for Anthony Ervin, on 47.09 in the 100m freestyle; Jessica Hardy, on 1:04.86 in the 100m breaststroke; and Michael Klueh, on 3:40.23 in the 400m freestyle.
New Zealand's Matthew Stanley clocked 3:42.21 for second behind Klueh, while Kiwi teammate Melissa Ingram took the 200m backstroke in 2:05.39, Hosszu settling for fourth place and a rare podium miss on this tour.
After Inge Dekker (NED) claimed the 100m butterfly in 57.39, she returned to the podium for second place, on 24.40, in the 50m free behind Britta Steffen (GER), on 24.01. Stanislav Donets (RUS), on 49.49, was the sole sub-50sec swim in the 100m backstroke.
After the second day of action in Tokyo, the tour concludes in Singapore at the weekend, the best man and best woman of the circuit in line for a $100,000 prize each.