A 0.0000001% Demon King

Story:

The Great Demon King Astrea put each of the 72 Demon Kings to the test before giving them the order to destroy the earth. The Great Demon King gave each Demon King particular powers once they prevailed in the trial and gained the title of Demon King. Every Demon King had been bestowed with exceptional powers thus far. The Great Demon King gave Karos a power when he turned into a demon king, however… "Great Demon King, there is a problem with my power, no matter how much I consider it." "Is there an issue?" Karos was given the "Gacha" ability among the Demon Kings' amazing powers. "Gacha as a Demon King's Power? With Gacha, how am I meant to control the world?