You were killed off by the villains since you were known as the greatest hero in history

Katsu was the new great hero but not better than you. Him and other heroes were winning the battle against villains, and the villains became desperate "SUMMONING OF THE DEATH" The villains had summoned you under their command "These shapes and colors overwhelm my vision. losing power, oh, I'm losing power" You said chanting a spell on the heroes against your will