Asia Argento

A second-year student at Kuou Academy. Originally a sister who was known as a holy maiden due to her healing powers. She was raised in an orphanage and was taken in by the Church after her powers were discovered. However, she was kicked out of the Church for healing a Devil, and was taken in by people affiliated with the Fallen Angels. She starts living with Issei after being saved from the Fallen Angels' grasp. As a person raised in the Church, she lacks common sense.

After she starts living with Issei, she shows that she has feelings for him but he dismisses this as her looking at him like a brother. When Rias moves in, she becomes increasingly more daring in her attempts to win Issei and views Rias as a rival in spite of their sister-like relationship. At the end of Volume 6, she kisses Issei and he realizes the true depths of her feelings.