Sera was kidnapped from Earth as a child by the evil Mutant Army Guts and taken away as a test subject, narrowly escaping brainwashing and modification thanks to rescue by the people of Shine Planet. Raised on Shine Planet, she grew into a warrior known as part of the "Shine Five," fighting alongside her comrades against the Mutant Army Guts. The Mutant Army Guts, led by commander Zoh Wamzee, continued developing horrific mutations, culminating in the creation of the monstrous mutant beastman Gi Garuzasu. The Shine Five needed to periodically return to Shine Planet to recharge their Shining Power, taking turns to do so. One day, while Sera was left alone defending Earth, the Mutant Army Guts attacked the city, sparking a fierce battle. Sera confronted the enemy, transformed into Yellow Shine, and fought against Garuzasu, but during the fight her energy ran low, weakening her ultimate attacks and gradually forcing her into a disadvantageous position.