The 901st Anti-Tank Troopers, also known as "Gespenst Jäger"(Ghost Hunters), are a secret experimented group of infantry specially trained to take on tanks. The platoon members are often distinguished by wearing a small steel-blue lantern on their persons. When opening the shutters, the members enter a sort of trance, which makes them unafraid of the targets they faced. They are brazed with the chant: töten sie or the command to kill. Dr. Kauplan was in charge of the development of the troop.
The 901st was not commonly known among the members of the Imperial Army's armored units, but strangely rumors were circulated within the Army about facing them. The rumors said that, if one should ever encounter a soldier with the lantern, they are not to be considered your friend, but at the same time they should not be made an enemy... that the lantern is a furnace that burns in their souls!
September 9th is when the Empire's first emperor died in battle, and so the military has an unwritten rule not to use the number 9 in its army designations. In addition, there are no records of the group in the military’s complete book. That is why the 901st A.T.T. were called the Invisible 9.