User blog comment:Traditionalfire/Why are all Ninjas women? (In games)/@comment-4961148-20120916200518

The brevity of your list really doesn't prove very much. You have only provided five games in which ninja-like characters are exclusively female. There are quite a few games in which one meets or plays as male ninjas.

But there's no particular reason for the "trend" you've observed other than the fact that game designers (and consumers) find it aesthetically pleasing. I am personally indifferent to it. When facing ninja-like enemies, I barely notice their gender, as I am more focused on how annoying their skills can be.