Superior

A hero is chosen to defeat the Demon Queen, whose rule has brought powerful monsters and the deaths of more than half the world's population. But he doubts the justice of killing monsters, believing they are conscious beings who deserve to live. Sheila, the Demon Queen, takes an interest in the hero and joins his journey in disguise, intending to kill him once she has earned his trust. As she comes to love him, their journey takes an unexpected turn.