比奈森 沙耶

Yamato Nadeshiko who serves as the guardian and caretaker of Naoya and Ichika.
However, despite her delicate and elegant appearance, she is a skilled swordsman unmatched in her family and though she appears to be a young girl, her exact age is unknown.

Since ancient times, she has offered absolute loyalty and selfless devotion to the Itsukino clan leader.

She is both a sword teacher and a mother figure to Naoya.