ソニア "S" インチェスター

The student council president at Yakumo's academy and her senior by one year.
Her parents are diplomats, and she is a noble lady descended from ancient Indian royalty.
She has a strong sense of responsibility, yet treats everyone equally kindly, holding an “older sister” position within the academy.
She can be a bit intimidating, but Yakumo, who doesn't mind that, feels like a somewhat troublesome little sister to her.

After being possessed by the Divine Skeleton Princess Sukanaha, her personality becomes knightly.
She transforms into a strict, high-and-mighty persona towards both herself and others, often clashing with Yakumo.
However, this stems from her resolve to protect her comrades, even at the cost of her own sacrifice.