Kage (OVA)
English name: Shadow
Genres: Action, Hentai
Type: OVA, Episodes: 4
Aired: Mar 26, 2004 to Dec 26, 2004
Studio: APPP
Source: Original
Rating: Rx - Hentai
Synopsis:
It is the peaceful Edo period in Japan, and ninjas are hardly needed anymore. Karyu, a particularly skilled ninja, is forced to do work as a hired killer. She is asked to kill a merchant, but when she gets there, she finds that his servant is actually a ninja, who is just as skilled as Karyu. Her name is Uzume. Karyu and Uzume then compete against eachother in a bloody battle for superiority. 

(Source: ANN)