It was developed by Mao Industries at the request of the Earth Federation Army's Far Eastern Base, and was the first PT created with EOT. It's the successor to the Gespenst MK-II, and the machine which it was based upon, the Wildschwein.
It's equipped with the Black Hole Engine, which was found from Meteor 3. With that as its power source, it easily out performed most machines created at that point. It's able to use a powerful weapon due to it, which is called "Black Hole Cannon."
The R model was involed in an accident during its initial testing on the Moon, in which it was destroyed, blowing up most of the base, and killing many people. It was referred to as the "Vanishing Trooper" after this incident.
The L model was stored away on the Moon after the R's accident, and wasn't piloted again until Ring Mao decided to use it during the L5 war.