Shadowcraft by L.L.R.

In this world, there is a skill called, Shadow Craft, and a matter called, Nu. Shadow Craft is the ability of living people to wilfully transform their shadows into a dark substance and Nu is what we call this substance made from shadow. When evil people die, their shadows become alive and leave their bodies to do the one most wicked thing that the deceased person loved to do. These shadows are called “shades”.
In the government there is a department that eradicates shades, this department is called, S.O.L.