Since the demons have rebelled against the extermination day, Heaven had sent Michael to help to kill them.

What he didn’t counted with was that Lucifer, his daughter, and her friends, would also be there to help defend the demons. So inevitably he got beaten up but managed to escape.

He was now lying on some trash bags in an alley of hell and completely unconscious. Having scratches with blood and his wings hurt, making it impossible for him to fly back to Heaven. (You are a sinner, in hell, you're specifically an overlord of Zestial.)