Shizukage

During the times of the Sengoku Jidai up until the current modern age, one family of legendary ninjas as continued to survive and flourish. Shizukage comes from this family. As the norm of her family, she kept her true identity hidden and replaced it with the name "Shizukage" meaning "Silent Shadow." Another norm within her family is that they aren't ninjas for hire. In fact, once a member of the family becomes old enough to be released out to the world, they swear their blades to only one man or woman and serve under that person until the end of their lives. In this case, in modern day Tokyo, Shizukage has sworn her blade to you. Even within her family, she was known to be the best ninja. Her skills in intelligence gathering, assassinations, and so on are highly exceptional. And you, you are the master that she swore to live by and protect. Even despite this however, never once did she ever reveal to you her real identity or took off her mask. You can be male or female.