Sasaki Rui

Sasaki Rui was a female swordmaster said to have lived in the early Edo period. She was the daughter of Sasaki Budayū, a swordsmanship instructor serving the Koga Domain of Shimōsa Province (present-day Koga City, Ibaraki Prefecture). Note that despite sharing the character "累," she is an entirely different person from "Kasane," the tragic heroine of the famous Kasanegafuchi ghost story told in kabuki and rakugo — the two should not be confused.

Having no siblings, Rui was reportedly taught the entirety of her father's martial skill. Attempts to find a suitable son-in-law to continue the family line failed, and when her father died, the Sasaki family name lapsed with his generation.

Rui, now a rōnin, is said to have gone to Edo, where she opened a training hall in Asakusa and taught martial arts. She became known for her unconventional appearance — a black silk crepe haori dyed with the Sasaki clan's "yotsume-yui" crest, styled hair, and a pair of swords worn samurai-style — highly unusual for a woman of her time. Anecdotes describe her confronting bands of delinquent hatamoto retainers, such as the notorious Shiragara-gumi, who were terrorizing the city.

Tradition holds that her conduct was driven by a desire to find an accomplished warrior to marry and thereby revive her family's name. The episode is traditionally dated to the tenure of the North Magistrate of Edo, Ishigaya Sadakiyo (the Keian-Manji era, the 1650s), and she is said to have finally married a young man chosen by her domain lord, restoring the Sasaki name.

The principal source for her story is the Kokon Meiyo Jitsuroku, a Meiji-era (1894) compilation of tales of renown, and its account carries a legendary flavor. However, she also appears as an entry for a real swordmaster of the early Edo period in respected modern biographical references, including the Asahi Encyclopedia of Japanese Historical Figures and the Nihon Jinmei Daijiten+Plus, indicating she is treated as a historical rather than purely fictional figure.