They appeared like stars, but their arrival was disastrous. They are referred to as the 'Star Creatures,' the invaders of Sheer.  "Hanister, would you believe if I said that the shooting stars are still alive?" Sheer was a planet covered by land. A serene, peaceful, and placid planet. Half a century ago, the Star Creatures descended out of the blue, catching the residents of Sheer off guard. The creatures dropped from the sky like a cluster of resplendent shooting stars. They are enormous, with incomparably powerful strength, as well as layers and layers of thick shells that coated around their bodies. The Star Creatures became the nightmare of Sheerians, the people of Sheer, since nothing can penetrates through their solid, steel-like shells.  They could not be defeated, neither could they be killed.  The world was completely ruined, civilization collapsed. The ones that survived started fleeing, hiding, trying to hold on whilst at death's door. At last, after a long period of time, human finally discovered the enemies' secret on operating the shell.  Therefore, the people of Sheer formed the 'Star Defense Alliance.' In order to make their own heroes, and fight against the invaders.  They were destined to be born and fight for survival.  They call them 'Chasers,' the Shell Wielder from Star Defense Alliance, the heroes of Sheer. Decades have passed, the invasion of the Star Creatures never once stopped. However, the rebellion of the Sheerians was just beginning.  ． Hanister Dyner "I couldn't save my own father, but I can save the others." Hanister was a girl born and raised in the crops section. What happened to her father had accidentally become the reason behind her joining the Star Defense Alliance, and the goal that she had been looking for.  ． Gadina "If we're all dead, what's going to become of the future of this planet?" Gadina came from Rodenzel, a busy, lively city. To leave her underground life behind, she decided to turn away from the organization that she had been working with for years, and joined the Star Defense Alliance's project on training new hunters.  ． Jensen Cavil "What if we are the creature that's destined to be eliminated?" As the apex hunter for the Star Defense Alliance, Jensen's shell-wielding technique was better than everyone combined on Sheer. However, as he watched the enemies fall to defeat over and over again, he only felt conflict and perplexity deep in his heart. Then again, he must continue on the journey of endless battles to resolve the confusion and seek the truth.