Lurking in the background of the impending Tokyo Olympics are various curiosities that seem to resist any attempt at co-option or beautification, offering potential respite from that upcoming sporting behemoth and its crowds.

One such curiosity is kyōtei (boat racing), a kind of slow, aquatic NASCAR that also happens to be one of the few things that you can legally gamble on in Japan. Six motorboats vie for top spot as they take three laps around two buoys — a simple endeavor that belies a great deal of skill.

Hidden in plain sight, kyōtei is an easily accessible facet of national life, owing to its central role in Japan's betting landscape. Twenty-four stadiums are dotted across the country (bar Hokkaido, Tohoku and Okinawa); my own port of call has always been Heiwajima in Tokyo's Ota Ward, a notably drab part of town that occupies similar psychological terrain to post-industrial parts of Kawasaki. Kinkakuji temple it is not, yet Heiwajima is no less interesting, providing a portal into a different, somewhat darker side of Japan.