Lady Snowblood - Resurrection

Japan in the time of the Meiji dynasty is a country in transition, torn and dominated by exploitation and moral decline. Lady Snowblood want's to leave her bloody past behind her and is working under the name Kashima Yuki in a girl's grammar school where she teaches Swedish gymnastics... but conservative political forces are like a thorn in their side, and Yuki must again take up arms to keep the promise she gave to her life-saver.

(Source: Carlsen Manga)

Originally serialised in 1973, but not collected into book form until 2006.