Colorless Vol. 3 (manga)

A cosmic disaster changed the Earth forever, stripping away every last drop of colour 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 colour.

He soon crosses paths with a very special girl--one who just might hold the key to bringing back what the world has lost.