Shoukan! Kengou Gakuen

This is the story of an all-girls kendo high school. All of the girls there are descendants of famous swordsmen from Japan's history. One girl is a relatively new transfer student, Hanyu Jubei, and a descendent of the famous Yagyu Jubei. She has never practiced with a sword, though it is in her ancestry. On her sixteenth birthday, the high school has a friendly match with another school, whose all-male team is dismayed to be roundly defeated by little girls. If Jubei is going to win her match, though, she will have to find a way to unlock the power of her ancestor.

(Source: MangaHelpers)