Star-Powered Mecha: The Boy with Cancer

The Fifth Cosmic Era:

Before the great calamity, humanity and machines, known as intelligent machines, depended on each other. By making use of them, humanity became the rulers of the cosmos.

While exploring unknown regions of space, the intelligent machines suddenly mutated and betrayed humanity, turning their weapons against their creators. Humanity, heavily reliant on the machines, was massacred, its population plunging from hundreds of billions to tens of billions.

The Blue Sea Star Federation was paralyzed. As three great cosmic races invaded, with humanity facing extinction, a golden beam of light shone upon a man called Pan at the Solar System's final line of defense. Pan was as large as Blue Sea Star. With two swings of his axes, he wiped out the invaders' vanguard and dealt a heavy blow to their main forces. At the cost of his body's energy disintegrating, he protected the Solar System for decades, until humanity's genes completed their mutation. The powerful stellar energy allowed humans, war beasts, and mechas to venture into the cosmos once more.