He controlled almost all the healing smoke in the magic world besides the smoke from Noi. Having his own fortress and henchmen to guard his products, he became a powerful elite Magic User selling his priced smoke to a quite high price. When the Cross-Eyes needed healing smoke for their companions Dokuga infiltrated Shaitan's store (disguised as a lady) in one of his various parties to fool around with women, then the Cross-Eyes poisoned the food and killed everybody there with his poison, Shaitan included.
Later Dokuga slaughtered his remaining workers and stole all the heal-type smoke. This incident would be later addressed, with En starting an investigation to know the responsible for his death.