Hanatsukihime

A girl named Lys was born without a heartbeat, and her mother secured her life by making a pact with a devil: he would lend her his heart until her sixteenth birthday, after which he would consume her body. Accompanied by Siva, a person she encountered in the desert at night, Lys performs as a dancer while searching for the devil who holds her fate. During their journey, they unexpectedly encounter a self-centered prince and a ring spirit. The first volume features a bonus manga, and the second includes a one-shot.