Cage

Sakimi, a student, finds herself in a pinch. Having been betrayed by her previous boyfriend, she finds herself in incredible amounts of debt. She turns desperate, and seeks help from a man who runs a "gentleman's service", who confines her to a room 24/7, only allowing her out to preform her tasks." In there, she discovers Mana Fujidoh, a mysterious young girl. Sakimi seeks to break the bonds placed on her, and free her and Mana from this hellish world of sexual desires and cosplay perversions.

Source: ANN