Jidaimono (時代物) are Japanese kabuki or jōruri plays that feature historical plots and characters, often famous samurai battles.
As the stereotypical audience for jōruri and kabuki were the merchant classes (chōnin) of Edo period Japan, stories involving court nobles and heroic samurai were somewhat far removed from daily life, and the more everyday stories that dealt with contemporary, urban themes.
However, the historically false conceit that certain Taira clan generals survived and remain in hiding is central to the plot.
The famous play Kanadehon Chūshingura, also known as the tale of the forty-seven rōnin, is one example; though the actual forty-seven rōnin and the events surrounding their attempts at revenge for their lord took place in the early 18th century, only a few decades before the play debuted, it was depicted onstage as taking place in the 14th century, with the names of all the principal figures involved being changed.
Generally speaking, many of the most flamboyant kabuki plays are jidaimono, as they tend to feature over-the-top representations of samurai heroes and villains, kami, and some of the most famous figures in Japanese history.