"An heir of the royal Poppy Dynasty will defeat the Demon Lord." That prophecy became nothing more than empty words after the demon army won the war. Blamed by an enraged populace, an eighteen-year-old princess is sent to the Floating Castle as a tribute. She loses everything, her family, her status, even her power, and has nowhere left to turn. If she wants to survive, she must compete with over a hundred concubines and seize a chance to assassinate the Demon Lord. To destroy evil, reclaim her honour, and silence her critics... She must share a bed with the Demon Lord and her wife...!?