Hunter Guild no Ura Quest: SSS Rank no Watashi nara Ecchi Quest mo Yoyuu (?) desu

A world where Demons run rampant. Those who hunt those Demons also existed. The SSS-Rank Hunter "Cynthia of the Silver Sword" is one day introduced to an "Underground Quest" that is said to offer a large reward. However, that was an Ecchi request in name only, far from actual exorcism...!? The Fantasy - Ero Quest conquest tale begins here! (Source: Akita Shoten, translated)