The Japanese ninja are known in the west mainly by the romantic image of the secret agent, or assassin, endowed with superhuman powers. Yet there is a lack of serious scholarship on the actual warriors who became the subject of the myth. This paper seeks to use the full extent of primary sources from the period to offer a blueprint for a historical, rather than mythical understanding of the ninja. They did not belong to a unified class, but were instead a hodgepodge of heterogeneous groups, united only by their skills in irregular warfare. They became “ninja” only retrospectively, as a result of the historical imagination of later generations.
