People who use ninjutsu (忍術, "art of stealth and endurance") are called ninja (忍者, "person of stealth and endurance"). Ninjutsu is not a combat technique but a strategic art of warfare that was developed independently in the Iga and Kōka regions of Mie and Shiga Prefectures. Sometimes ninja are portrayed in films and in manga (漫画, "Japanese comics"), flying the skies, disappearing without a trace and fighting enemies with ninja swords like a superman.
But the job outline of the real ninja primarily consists of two things; gathering secret information and plotting strategies. The techniques for doing these tasks are summed up as ninjutsu. The intelligence activities of the ninja are similar to those of spies today; ninja gathered and analyzed information about the enemy's military strength. The strategic activities were techniques that decreased the enemy's military strength. The ninja would not fight enemies stronger than themselves. They would normally gather information about the enemy and think of ways to defeat them without fighting.. They had a reasonable way of thinking, and based their tactics on their belief in intellectual powers.
The roots of the ninja go back to 4000 B.C. when the culture of ancient India was brought to China, and were handed down to Japan in the 6th century A.D. over the Korean Peninsula through the art of warfare. The art of warfare introduced to Japan from China evolved into Japan's own, and from there a specialized art of warfare called ninjutsu split off and was further developed in the Iga region. The ninja are the unknown warriors of the shadows. Who knows, maybe they exist still today? If you want to find out more about the ninja, don't miss the chance to go to Iga!