Humanity joined forces to kill the demon king but they didn’t expect that the demon king was to OP

I rate this Manhwa: 9/10 The Demon King Is Main Character And The hero is the Heroine😍 Humanity joined forces to kill the demon king but they didn’t expect that the demon king was so strong, the demon king was about to destroy their army but suddenly the hero came and stopped the demon king, The demon king was surprised by the power she show