Chisato Hasegawa serves as the school nurse at Hijirigasaka Academy, distinguished by her long black hair, green eyes, a mole beneath her left eye, and a voluptuous figure. Her professional attire typically includes a green turtleneck, black miniskirt, cross-gartered stockings, and a white lab coat. Her private clothing choices range from elegant winter coats to revealing swimwear like a green sling bikini. Her true identity is later revealed as Afureia, a former high-ranking member of the Ten Gods from the Divine Realm. As Afureia, her hair becomes golden-blonde, her eyes shift to blue, and she manifests wings of light.

Her personality merges calm mentorship with intense personal devotion. She offers wise counsel to students, particularly Basara Toujou, despite her own lack of romantic experience. Initially mysterious, she develops deep romantic feelings for Basara, entering a secret relationship where she willingly accepts his advances. This relationship sparks jealousy when Basara focuses on other girls, leading her to tease or punish him. Her loyalty to Basara ignites protective fury against threats to his life, like Ornis. As their bond strengthens, she embraces masochistic tendencies, desiring to relinquish her divine status and become his submissive partner, viewing this fall from grace as deeply taboo.

Fifteen years prior to the main events, as Afureia, she witnessed her older cousin Raphaeline (Basara's biological mother) punished for bearing a child with a hero and demon. Unable to intervene, she honored Raphaeline's wish by delivering infant Basara to his father, Jin, in the Human World. She then relinquished her position among the Ten Gods, had her powers sealed, and adopted the human identity "Chisato Hasegawa" to watch over Basara. In the present, she mentors Basara through supernatural conflicts while hiding her divine origins. Their romantic involvement culminates in a Master-Servant Vow, reactivating her full goddess abilities. By the series' conclusion, she is pregnant with his child, linked maternally to other expecting characters in his harem.

As a former Ten God, Chisato possesses immense divine capabilities, initially limited by seals. She demonstrates superhuman strength, such as catching Basara's demon sword barehanded, and can manifest energy blasts or magical restraints. Her abilities include memory alteration, illusions, and blessings granting resistance to hostile magic. A unique temporal manipulation power allows her to compress time within barriers—for instance, extending one night into a year and a half with Basara. After forming the Master-Servant Vow, she regains full goddess powers, including a maternal link that synchronizes pregnancies, suppresses morning sickness, and shields unborn children from harm during physical exertion. She also exhibits exceptional stamina, mastery of advanced magic, medical expertise, and charismatic influence.