Japan is full of unassuming signs marking the sites of historical significance of varying degrees, from a samurai lord's residence to a long-defunct elementary school, to the birthplace of some local delicacy. In the historic Tokyo downtown of Sumida City, there is a series of historical markers called Onihei Jokei, dedicated to fictional events that took place on the spot.

Onihei Hankachō was a popular jidaigeki novel series written by famed author Shotaro Ikenami and serialized from 1967 to 1989. It has been adapted into other forms of media numerous times, including four TV series, two films, an anime miniseries, and a manga adaptation by Takao Saito ongoing since 1993. It follows the fictionalized adventures of Heizo "Onihei" Hasegawa, a real-life investigative officer who specialized in cases of theft and arson in the feudal Edo period.

Installed by the city government in 2013, 16 historical markers in Edo style point out the locations of the novels' events and the local history that inspired them, blurring the line between fiction and real life.