From the ancient times, Samurais in Japan utilized swimming as part of their military training. Surprisingly, by the late 19th century, despite the tradition, Japan did not have the resources to compete against larger countries such as Great Britain, Australia, and USA when swimming emerged as an international competitive sport.
In fact by the inception of the Olympic games they had only 2 competitive pools in all of Japan. In 1920 at the Antwerp Olympics they did not even enter swimmers.
But by 1928 at the Olympics in Amsterdam things started to change. That was the year an obscure railway worker, Yoshiyuki Tsuruta won the gold medal in the 200-meter breaststroke. Only the second Japanese Olympic gold in any sport!
Pretty much all of Japan caught swimming fever and the perception of swimming was forever changed.
Japanese Men's 1932 Los Angeles Olympic Team
Taking a more scientific approach, the Japanese began studying the strokes. Even incorporating underwater cameras to help better understand the mechanics of entry, catch and pull. Significant improvements to freestyle and backstroke, specifically increased shoulder rotation changed swimming forever. In the 1932 Los Angeles Olympics Japan won a staggering 11 medals. Yasuji Miyazaki won gold and Tatsugo Kawaishi won silver in the 100 Free. In the 200 Breaststroke, swim sensation, Yoshiyuki Tsuruta took home the gold medal Renzo Koike took the silver the. They won the 4x200 relay, swept the 100 backstroke. and Kuso Kitamura and Shozo Makino, respectfully won gold and silver in 1500 freestyle.
Nearly one hundred years ago Japanese innovations changed swimming and incredulously, continue to impact and influence swimming to this day.