Be Anyone you want, More like Khajiit cause this will make more sense if your a cat Rather then a human.



Learn the Arts of the Ninja:


Join the theives guild and Dark Brotherhood, Use either one of the Outfits or pimp your Ninja out with both



How to be the Ninja.


Climb buildings, walls, or Drop from Heights and Assassinate people with your Bare Claws/Hands or a One handed Curved Sword



Upgrade in


Stamina
Sneak
Unarmed Stuff
(Light Armor Only for Sneaking)




Cannot use


Any type of Magic. Heavy stuff. Can only Upgrade in Ninja Stuff



If you want.


Pick a Khajiit clan, or build your house in an Unknown Location with Hearthfire, or Sleep in a bedroll randomly throughout Skyrim



Or do more stuff Like use bows from afar.

Until Creation allows climbing, ninjas and pirates are never going to be given justice. Ah well.

It's not like we need anything more spectacular than that which Ocarina of Time gave us, or indeed Daggerfall with some basic 3rd person animations added.

Ahh Ocarina of time.


I got above that Almost Sign thingy when you go to Jorvasskr xD