Sneakers are indispensable for exercise, especially during autumn, the season of sports. Japan is experiencing an unprecedented sneaker boom. The average Japanese person owns 6.8 pairs of sneakers. Further, Japan's sneaker culture is attracting attention from around the world. Sneakers aren't just fashionable but practical, and behind the boom were a variety of factors that are unique to Japan, such as functionality for making children run faster. We investigate the cools of Japan's sneaker culture.