Es was created by Sōichirō Unomaru as a back-up vessel for the Embryo, but she failed to obtain it, which can be seen by her red eyes. She could go into the Boundary without experiencing any of its negative effects, and later she obtained Hinata Himezuru's Embryo. Since Es returned from the Phantom Field as an ordinary human girl, she lost the Embryo Storage properties. The Embryo Storage is also called a Manifestation Boundary Interface Prime Field Device(示現境界接触用素体Jigen Kyōkai Sesshokuyō Sotai). ru:Эмбрё Сторэдж