Dr. Reigan led scientific efforts on planet S-1, directing a team focused on reversing severe environmental pollution from prolonged warfare. His research aimed to heal the ecological damage forcing S-1's population underground.

Military leader Zeo Gattler, intent on abandoning S-1 to invade Earth, targeted Dr. Reigan. During Gattler's coup, which included assassinating S-1's emperor, Dr. Reigan and his team were framed for the emperor's death. Gattler's forces then attacked the laboratory, killing Dr. Reigan and his fellow scientists and destroying their environmental restoration research. His death occurred as his son, Marin Reigan, attempted to intervene.

Miran, acting under Gattler's orders, carried out the murder. Miran's sister, Aphrodia, witnessed the killing, igniting a cycle of vengeance between Marin and Aphrodia. This event catalyzed Marin's escape from S-1 and his decision to defend Earth against Gattler.

The narrative later reveals S-1 is a future, ecologically devastated Earth. Dr. Reigan's work represented a potential solution to prevent the environmental collapse that would eventually force humanity to flee. However, Gattler's actions—destroying the research and invading Earth—directly caused the same environmental catastrophe that originally doomed S-1, establishing a stable time loop. This loop underscores the significance of Dr. Reigan's unrealized environmental restoration efforts.