Heroes of the Far East: Ninja (2010)

From the Publisher:

Samurai may rule the open battle field, but not all battles are won in the open. Sabotage, espionage, and assassination are the tools of the ninja, and these can do far more damage than a clever flanking maneuver. Those obsessed with codes of honor often look down upon the ninja for what they perceive as shameful tactics, and many believe all ninja are ruthless mercenaries who sell their services to the highest bidder. While true of some ninja, many ninja dedicate themselves to serving a particular lord or to protecting the less fortunate.