Etana, the eldest daughter of the wealthy and influential Gloria family, lives among her four sisters—Sicile, Mary, Naomi, and Charme—within the family mansion. Her character is defined by a strong-willed personality, setting her apart from her siblings.

Shortly after his arrival at the mansion, Georg Hanson, one of two elite tutors hired by the family, selects Etana as his pupil. This occurs before the other tutor, Kira Akishino, begins instructing the remaining sisters. Etana's narrative unfolds primarily within this tutoring relationship, situated against the backdrop of concealed family secrets and external threats targeting the household.