Tsukasa is the female protagonist of the Devils' Line series. She is a first-year graduate student at Keio University where she originally studied Humanities and Geography. She is a kind-hearted human girl who falls in love with Yuuki Anzai at almost first sight. Despite the difficulties of being in a devil/human relationship, she stays positive and is always trying to make it work. She cares about Yuuki and his suffering as a devil very much and is constantly looking for something she can do.