Yoshikuni XI

A descendant of the one who forged the Kurikara, Rin's sword. She seems easygoing and friendly. She is especially nice towards Ryuji, and calls him "Ryu-chan". The two are childhood friends, and she even embarrasses him by mentioning that he was in love with her and asked her to marry him.

She remains nameless and is an anime only character.

(Source: BlueExorcist.wikia)