Due to depleting resources, toxic planet surface, and the threat of extraterrestrial beings, all the nations of Earth combined to create a central government; The Earth Unit. While working under this new government, a brilliant scientist by the name of Dr. Aura discovered DNA of animals that once populated the planet... animals long extinct, such as dogs and cats. Using this DNA, he created genetically modified animal soldiers, called Bio-Units, to defend the planet from external threats. However, Dr. Aura's ego began to grow out of his control, and though time, became a tyrant ruling over his own creations. He overthrew the Earth Unit and took over as it's new ruler, using his Bio-Units as his army. Over time, these Bio-Units began to show their disapproval of Dr. Aura's actions, some even going as far as betraying the Earth Unit and running away, unwilling to participate in his tyrannical actions. Lars, a carefree and over-confident fighter, Kit, a softhearted mechanic, Deon, an arrogant ex-soldier, and Garrison, their strict team captain, teamed up and challenged Dr. Aura to put a stop to his dictatorship. After a strongly fought battle against his armies, the 4 of them succeeded in overthrowing Dr. Aura, and upon his defeat, took over the Earth Unit. Garrison, the team's captain, became the new head of the planet, and began to restore the relations between Bio-Units and the people of Earth. Peace became a reality, and a new era in Earth's history was beginning. However, word of Dr. Aura being sighted recently has caught the attention of Garrison, Lars, Kit, and Deon. It was under everyone's understanding that Dr. Aura was dead, defeated in battle years ago. Surely, he could not still be alive.