A gray Earth, where humanity was transformed into deformed beings. The curtains open on an action series where the goal is to recover a lost world, with the help of a strange-looking gun!

An enormous solar flare caused the planet to lose all of its colors. Humans are deformed and declining in numbers. The key to reclaiming the old world lies within the power hidden in color, and one girl. Knowing that the few remnants of colors in the world yield a great power, Avidia, who is conducting research while protecting a girl named Chie, uses the colors to expand his own power, and throws himself in a battle against the Cult.

A cosmic disaster changed the Earth forever, stripping away every last drop of color from the world. Mankind also changed: the familiar human face is almost forgotten in a world now populated wholly by mutants. Against the backdrop of a moody urban landscape, a lone-wolf investigator named Avidia relies on both his wits and extraordinary gun to hunt down the world's last hidden scraps of color. He soon crosses paths with a very special girl -- one who just might hold the key to bringing back what the world has lost.