All Things End (male child reader X adoptive mother Retsu Unohana)

After a fierce battle with Kenpachi Zaraki, Unohana died from her wounds and from the effects of her Bankai. After she was put to rest something strange happened, she woke up unscathed in a new world. She has little time to come to understand her new situation after she is unwillingly thrust into a role she never asked for.