Onnamao-sama ha Yuusha-kun wo Taosenai.

Demon Lord Abyss was worried... about not being able to defeat the hero, considered the mortal enemy of the demons. This hero is still an inexperienced young man - he should be easy to defeat!.... However, the problem is that he, not knowing Abyss' true identity, considers her his "master" and becomes very fond of her...!