In Japan, modern sewer systems began to appear during the late 19th century, though evidence of older sewage systems dates back to over 2,000 years ago. Foreign engineers introduced the Japanese to modern, underground sewer systems with above ground access points called manhoru (manholes). At first, Japanese manhole covers used geometric designs similar to those used in other countries. In the 1980s, when communities outside of Japan's major cities were slated to receive new sewer systems, the public works projects were met with resistance – until one dedicated bureaucrat solved the problem by devising a way to make these mostly invisible systems aesthetically appreciated aboveground: customized manhole covers. 

Because the Japanese elevate design in all aspects of life to a new level, the custom covers were welcomed, even though they cost more than generic ones. Today nearly 95 percent of the 1,780 municipalities in Japan sport their very own specially designed manhole covers. Designs range from images that evoke a region's cultural identity, flora or fauna to landmarks and local festivals.

Unsurprisingly, this phenomenon has bred another phenomenon: manhoru mania. A rabid online community, based in Japan and abroad, has developed around this city-sanctioned urban art. Several blogs and websites dedicated to manhole covers provide details about locations and designs. With numerous colorful photographs organized by region, Drainspotting is the first book to document yet another wholly distinct aspect of contemporary Japanese visual culture.