As the Earth Drop operations begin, the 603rd is assigned to test the YMT-05Hildolfrtransformable mobile tank. The task falls onto Maj. Demeziere Sonnen, a respected armored warfare instructor who is now disgraced and troubled by drug addiction from his own misery after Zeon abandoned armored vehicles in favor of mobile suits.
When the team drops intoArizonafor field tests, they find their assigned drop zone supply depot destroyed by a Federation assault team using captured Zakus. Sonnen is forced to bring the uncalibratedHildolfrinto battle. The fast and powerful mobile tank proves its mettle by taking out all enemies, but not without the cost of Sonnen's life.