4 years ago before the story, he kidnap Tsui-Ling from Kazuma so Armagest can use the girl as a human sacrifice to summon a powerful demon. Kazuma tried to stop him and save Tsui-Ling, but was no match for Erwin's powers. Erwin successfully sacrifice Tsui-Ling to the monster so he can gain it's power. As he was about to kill Kazuma, Kazuma made a contract with the Spirit king of the Wind and obtained the great wind powers. Erwin was killed by Kazuma's new power.