Do Japanese 'ninjas' really have stealth?

Invisibility is actually a technique in ancient Japanese Ninjutsu It is the use of the environment, to hide themselves, because most ninjas perform their tasks at night, so most of their clothes are purple or black And recluse in general terms is to hit the ground Once there was a ninja, very famous, but forget, he spent 3 days digging a tunnel, intending to assassinate some politician, but due to the continuous digging of the body of the smell of sweat attracted The smell of sweat from his body attracted flies, which were detected by the guards, who plunged a knife into the ground, hitting the man right in the heart.