The "ninjato" (or "ninjaken") is often depicted in popular culture as the preferred weapon of the ninja, typically portrayed as a short, straight-bladed sword. However, the historical accuracy of this weapon is subject to much debate among scholars.

There's no historical evidence from the period when ninjas were active (roughly 15th to 17th centuries) that proves the existence of such a sword. Most of the weapons and tools used by ninja were more likely ordinary objects, not specialized weapons like a unique sword.

The concept of the straight-bladed ninjato appears to be a relatively modern invention, possibly dating back to the 20th century. It was popularized in books, movies, and TV shows during the 20th and 21st centuries.

Therefore, the consensus among most historians is that the ninjato, as it's commonly depicted, likely did not exist in historical Japan. Instead, it's more of a modern, fictional invention.