Dozens of Japanese commuters pushed a 32-tonne train carriage away from the platform to free a woman who had fallen into the 20cm (8in) gap between it and the platform.
The act of collective heroism was captured by a newspaper photographer.
A public announcement that a passenger was trapped prompted about 40 people to join train officials to push the carriage, whose suspension system allows it to lean to either side, the Yomiuri newspaper reported.
The unnamed woman in her 30s was then pulled out uninjured to applause from onlookers at JR Minami-Urawa station, just north of Tokyo.
After just an eight-minute delay, the train went on its way.