Athena is an heir of the Tennousu family and is revealed to be one of the five directors in charge of Hakuou Academy in the manga. She has mainly appeared in the manga. She has only been shown in the anime during a brief flashback where Hayate reflects on his first girlfriend. Her parents are presumed missing or dead, since she lived alone. She is Hayate's ex-girlfriend, as well as his first Mistress, whom he met 10 years ago. Since he was very young at that time, he called her "A-tan" for short. He lived with her for a while at her castle "Royal Garden". There she taught Hayate how to do house chores such as cleaning and cooking. She even taught him sword fighting. She also healed Hayate's body and reinforced it with some kind of spell, which could be the reason for Hayate's power.