While the Earth was being invaded by Alien Empera, the Land of Light was simultaneously attacked by Alien Empera's vanguard—a massive army of Imperatormachines. The mainstays of the Inter Galactic Defense Force had all gone to Earth to support Mebius.
Consequently, the Inter Galactic Defense Force had no choice but to dispatch Ultras from various departments to fend off the attack. This left Alien Zarab an opening to break out of prison along with a bunch of aliens from the Dark Nebula amidst the chaos.
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Chapter 59