The demon queen who subdued enormous and powerful monsters, slaughtered over half of the world population. Surviving members of the human race elected a hero to slay the demon queen, beseeching release from her oppressive rule. His name is Exa the Hero. However, he questions his mission to eradicate the monsters for they too are alive and anguish over that fact. Sheila the Demon Queen became interested in his principles and joined his journey, hiding her identity. Eventually, she realizes that she fell in love with the hero and hence their journey began...