After two silvers and a bronze at the previous leg in Singapore three days ago, the British Gas ITC Bath swimmer continued her form with medals over each of disatances - 50m,100m and 200m Backstroke.
The 22-year old lowered her English record for silver in the 50m Backstroke, touching just 0.01 seconds behind Brazil's Etiene Medeiros in 26.62.
Simmonds' second medal came just 45 minutes later as she clocked 2:02.34 to touch behind Ukraine's Daryna Zevina (2:01.70).
She rounded off her performance with bronze in the 100m Backstroke on the second day with a time of 57.20 to finish just behind Emily Seebohm (57.09) and Daryna Zevina (56.87).
Having medalled at each of the previous six legs of this year's World Cup, Olympic silver medallist Michael Jamieson extended his record with 200m Breaststroke bronze.
The 25-year old touched in 2:04.32 behind Hungary's Daniel Gyurta (2:01.30) and Japan's Yasuhiro Koseki (2:03.63).
Sophie Allen was the third British medallist in Japan, reaching the podium for the fifth consecutive leg of this year's World Cup series with bronze in the 200m Individual Medley.
The British Gas ITC Bath swimmer clocked the second fastest time of her career to touch in 2:06.69 while teammate Siobhan-Marie O'Connor was seventh in 2:09.13.
Allen also lowered the English record in the 200m Breaststroke on the second day of comp with a swim that saw her finish fourth with a time of 2:22.65.
The swimmers will now head to Beijing for the final leg of the series which begins on 13 November.