Kage (OVA)
English title: Shadow
Japanese title: 影Shadow
Alternative titles: Hyper Shinobi Animation: Shadow
Type: OVA
Source: Original
Episodes: 4
Status: Finished Airing
Aired: Mar 26, 2004 to Dec 26, 2004
Duration: 29 min per ep
Rating: Rx - Hentai
Studios: APPP
Producers: Japan Home Video
Licensors: Super Techno Arts
Genres: Action, Hentai
Themes: Gore, Historical, Martial Arts, Samurai

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)