Kojirou Sasaki is a Master Samurai and a member of the Dark Samurai in the anime Hyakka Ryouran: Samurai Bride. She carries the soul of the legendary historical swordsman Sasaki Kojirō, who was famous for his duel with Miyamoto Musashi. In this series, she is a tall female swordswoman who has been reborn bearing the spirit of that legendary fighter.

As the most conservative member of the Dark Samurai, Kojirou relies on her intellect and strategic thinking as much as her physical strength. She possesses a strong warrior spirit and is drawn to testing herself against powerful opponents. However, she is cautious about entering a full state of war, as she worries about losing control of her dangerously volatile nature when fully unleashed in combat. Her deepest loyalties and feelings are directed toward Musashi Miyamoto, the reincarnation of her historical rival, to whom she is deeply bound.

Her primary ability is masterful swordsmanship, using a long nodachi. In addition to her martial skill, she possesses a sleeping mask that gives her the power to control and manipulate the minds of others. The tension between her sharp intellect and the explosive, volatile warrior spirit within her is a defining aspect of her character, shaping her actions and her relationships with the other samurai.