Men's marathon in Japan has seen 4 new national records in just the last 3 years. We take a look back over Japan's strong history of performance in the sport, and assess how developments in running shoe technology, most notably thicker soles, are impacting finishing times in the marathon. 2018 Boston Marathon champion Kawauchi Yuki discusses how athletes have been adapting their running styles and training methods to take advantage of the evolution in footwear.