The first mobile armor fielded by the Principality of Zeon during "The One Year War". A massive combat walker (robot), it featured multiple twin-barreled mega-particle cannons on its vaguely onion shaped body as well as the unique "Leader" anti-mobile suit weapon.
One unit fought the rx-78-2 at the Odessa mining division base while a second unit would be encountered and destroyed by a Ground Gundam during the Battle of Odessa. A third and possibly final unit was encountered and destroyed by the White Dingo team in Australia.
