Along with Iga, the Koka region is synonymous with ninja. The Koka Ninja are often depicted in anime and movies as the arch rivals of the Iga Ninja or as villains. But what were they really like?

KOKA, Shiga Prefecture--Like the furtive ninja groups it hosted in feudal times, this city in western Japan still has secrets to spill. In this latest instance, researchers discovered the first ...