Sae さえ
She was found in Magano in a carrousel without memories of her past by Rokuro , Benio and other Exorcists (Magano is the place where the kegares and Basara world where Exorcists fight).
Rokuro and Benio seeing her in Magano decide to bring her to the dormitaroy and next they decide to take care of her in Rokuro and Benio house.
Later to some problems in the real world they have to travel and later is revealed her past
She Loves Ohagi and is smart but with a childish side. Also shes very enthusiastic and she refers Rokuro as "Papa" and Benio as "Benio" but later she calls her "mama" in her OhagiMan Story