Although most of the chapters in the original "Blue Drop" manga are auto-conclusive, the first recurrent character and main protagonist is Yui, an alien/human hybrid introduced as a member of the resistance. Because of her alien heritage, Yui possesses their characteristic blue eyes, the white-colored blood, and their sexual orientation. Other recurrent characters include , an alien initially introduced as a school nurse but later shown to be working for the military, and , a high-school girl that Yui rescues from Misato.