Based on the game by Black-Lilith.

Taken prisoner by the main character, battle princess Lotte has ended training to be a slave made in order to prolong her life. Slave maids are specially trained maids traded among the noblemen. While providing sexual services, they also live by working as guards who put their lives on the line for the protection of their masters, making them very valued to both royalty and noblemen. The battle princess loses her virginity and has to endure dirty and degrading training in order to turn her whole body into a sex toy.