Ninjas (忍者) refer to the group of professional spies who flourished in the pre modern age in Japan. What kind of activities did ninjas perform? Firstly, as ninjas are spies, ninjas entered into enemy territories in secret and they ran away with top secrets of their enemies. There were various ways they went about their activities. Primarily, the methods centred about not being seen by anyone. For instance, a ninja would creep into a residence where lords of his enemies lived and eavesdropped on confidential conversations of important people. In this case, of course his targets paid close attention not to leak important information. They tried to keep when and where meetings took place a secret, and even in real gatherings, they took care never to speak loud. However, even in such cases, a ninja had techniques to steal top secrets from their foes.