In world overrun by monsters of steel and earth, risen from the depths of the planet, true power lies within one's mastery over their arsenal.
Countless "Exterminators", people with the ability to wield and transform a simple piece of stone into a tool for destruction, step in to shatter the chaos ensued by the primordial abominations of the Earth.
Zen, a witty and sharp tongued high school student who aspires to be an Exterminator has been summoned to choose his first weapon as part of the mandatory regulation. There, people with weapon shifting abilities are given the chance to shape their future.
Accidentally acquiring a weapon beyond comprehensible power, things take a turn for the worse as he's become a target for quite a sinister organization. With the mysterious broadsword in his possession, will he be closer to his dream of being an Exterminator or is he unknowingly being led to his doom?