I use something called K-On! Kisekae 2: here. You start off with humans, but with hexadecimal custom-colorization and some other features, they become furries.
So what you see as tanlines are supposed to be where the base fur ends and the second color fur begins.
This should clarify two comments someone made. Don't expect anything professional from me for the time being.
EDIT: It's now called "Minna no Kisekae! (Everyone's Dress Up!)" and is available for download from Enty (requires an Enty account).
