Sana Koishikawa, daughter of a healer running a sanatorium, follows naturally into her parent's profession. She treats both minor ailments and serious injuries for the surrounding community, maintaining close ties to the Tateoka family and others from their dojo within their social circle. This connection draws her into Shinjuro Tateoka's group as they confront threats endangering the town, particularly during the conflict involving the rogue samurai Mikage and the demands of the Tokugawa shogunate.

Her reserved personality carries a somber tone, often reflected in a saddened expression. While professionally committed to healing the injured, she holds a deep fear of her friends suffering harm, an anxiety persisting alongside her duties.

She possesses violet hair and violet eyes. Her background, role, and relationships remain consistent across all documented media.