That black slime is not just a slime it is the slime of darkness. korir a former army commander and presidential body guard is framed twice. First by his comrades in the army and after he gets a new job as a politicians body guard he is once again framed to save the politician work. He is given a death penalty for a crime he never committed. He is given a second chance when he reincarnates as a black slime. Armed with the knowledge of both milltary and politics from his past life he takes the form of a goblin and rules over them.