A Bounded One, is a slave whose body has been linked to a monster by a ritual performed during childhood. Being connected by a special vine like an umbilical cord, the two, both the slave and monster share their lifespan, thus allowing the Bound One to control powerful monsters, therefore turning them into a sort of human weapon. Discrimination is common against Bounded Ones therefore they often suffers abuse at the hands of different people alike. Eiha is a Bounded One and suffers the subsequent abuse after joining the Revolutionary Army.