She is the Holy school's martial arts instructor and sister of Chiaia. Unlike her serious sister, Mexiah indulges in her hedonistic nature and is shockingly affectionate toward Kenshi or even other girls. It is Mexiah who discovers that Kenshi is easily infulenced by hypnosis, which she uses to turn Kenshi into a massaging machine. Mexiah walks around in little clothing often, thinks nothing of it, and even sleeps with multiple female students at once. Mexiah is able to sense quickly that Kenshi is far superior to her in swordsmanship, and therefore doesn't need to take sword classes, as no one in the Holy land is of a close enough level to him to teach him anything. It is later discovered that she is not Chiaia's real sister, but was discovered by Chiaia's father in the same ruin in which the Seikishin was found.
Mexiah's inner form is Doll, one of the three man-made seikishi made to destroy Gaia. After Doll re-emerges to fight Kenshi, she is unable to hurt him because of Mexiah's memories of him. Doll becomes influenced by Mexiah's experiences and feelings for Kenshi, causing her to express new emotions.