From Baka-Updates:

The demon queen subdued enormous and powerful monsters and slaughtered over half of the world's population. Surviving members of the human race elected a hero to slay the demon queen, beseeching release from her oppressive rule. However, he questions his mission to eradicate the monsters: in his opinion, they too are conscious and alive, and so he anguishes over that fact. Sheila the Demon Queen became interested in him and joined his journey, hiding her identity and with the plan to kill him after she has gained his trust. Eventually, she realizes that she fell in love with the hero, and hence their journey begins...

(Shoutr's note: despite my tries to rename the images and the chapters so they can be read without the aid of a schizophrenic masochist, i might miss some inaccuracies in the chapters followup, don't blame me, blame the weird scanlation release.)