Onnamaou-Sama Wa Yuusha-Kun O Taosenai.Onnamao-sama ha Yusha-kun wo taosenai; 女魔王様はゆうしゃくんを倒せない。

Demon King 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...!