Nobunaga no Shinobi

This 4-koma manga follows Chidori, a little ninja girl in Sengoku Japan (the Warring States Period). One day, Oda Nobunaga himself rescues her from drowning in a river. Since that day, Chidori knew she wanted to serve Nobunaga. 5 years later, she and Sukezou (who likes her) head out from their ninja village, determined to serve Oda Nobunaga!

(Source: MangaHelpers)