Okay, there's been so much debate over Koujirou's gender that it makes my head spin. Final conclusion: Koujirou is female. See the game ending for proof. The reason she's running around with a male name, doing male things, is that she's taken on the identity of her recently deceased brother, in order to find his killer. So yes, we're supposed to think she's male. Despite this (^_^) I like her quite a lot; she's a strong, interesting character.
Koujirou is, not suprisingly, quite similar to Keiichirou in gameplay; it's a Shinsengumi thing. ^_~ She still has her own style, though, and a regiment of moves that are quite fast. I don't play her a lot, but she's solid and can really kick arse provided she doesn't concentrate only on her moves that deal with airborne opponents.
Last Blade 2 Story: Koujirou is captain of the Shinsengumi Unit Zero. 6 months ago their investigation into Hell's Gate became Keiichiro's solo mission; and at this time, Shikyo escaped from their number. Many of them were lost in the battle with the crazed Shikyo, and the Zero Squad came to question their purpose. But the Hell's Gate investigations had to be carried out. And so Koujirou travels to Hell's Gate, to restore the Zero Unit's faith in themselves, and to defeat the crazed one who slipped through their fingers.
Useless but fun facts: Although I'm not aware of her birthdate, Koujirou is 30 years old at the time of Last Blade 2. The kanji for her name (or technically, her brother's name) means something like true rice field for Sanada and next small son for Koujirou.
Kaede | Moriya | Yuki | Shigen | Hyo | Keiichiro | Shikyo | Juzo | Akari | Zantetsu
Recca | Okina | Kagami | Musashi | Setsuna | Hibiki | Mukuro | Kouryu