From publisher blurb:
Bring the ninja to your original edition games! The ninja has been represented in role-playing games from the days of the earliest edition but has been plagued by imbalance and fallacies. The Eastern Expeditions™ line aims to address these issues.
Eastern Expeditions: The Ninja provides a complete character class, as well as Japanese weapons, armor, and equipment suitable for a ninja’s use. The class is written for the Delving Deeper RPG, but with minor modifications could be used with any “old-school” RPG, including the advanced editions of the original fantasy game, Swords & Wizardry, and OSRIC!