In an era where the once-prosperous scientific technologies have declined, a new energy source called "magical power" drives the world. Humanity has created the forbidden biological weapons known as "Gears." The Gears, upon their creation, eventually rise in rebellion against humanity.
The ensuing "Holy War"—a war for survival—sees humanity emerge victorious, but at a great cost. Even after more than a decade, the scars left on people’s hearts have yet to heal.
Shin Kisk, the child born of the forbidden union between a human and a Gear, is on his way to his parents' wedding. This is a union long seen as taboo—human and Gear marriage, something achieved only after a long struggle in peaceful times. The wedding is surrounded by conflicting emotions, yet it remains a ceremony full of blessings.
Suddenly, a mysterious girl appears—an inheritor of the Gear bloodline, and one who harbors deep hatred toward the Gears. The encounter between the two, a child of destiny and a girl who despises the Gears, will send shockwaves throughout the world.