Isn't this Ayame from Tenchu?

Certainly looks like it if you look at other pictures of Ayame on danbooru. Investigate and tag next time, alriiight? *v*

Tenchu Z, Probaly not ayame/ But custom char's.. Maybe.

The G-string's a nice touch.

Added the tag Tenchu Z since I agree with Yuffie67.
Looks more like Tenchu Z than Ayame even though it certainly has a resemblence.

also agree with Yuffie67 and Zeithri.
The custom char is the only one who has a half naked costume model. Ayame, unfortunately, doesn't.