Theme 1; Kemonomimi
Kemonomimi refers to humanoids, taking on animalistic traits. Traditionally, this comprises of cat ears, and tails. There are a lot more subsidies of this though, and we can even define them.
Nekomimi

Taking on the appearance / traits of a Cat
Kitsunemimi

Taking on the appearance / traits of a Fox
Inumimi

Taking on the appearance / traits of a Dog
We've also got; ( Caution: Some NSFW )
Usagimimi: rabbit ears
Ookamimi: wolf ears
Hitsujimimi: sheep ears/horns
Umamimi: horse ears
Ushimimi: cow ears
Toramimi: tiger ears
Nezumimi: mouse ears
Kumamimi: bear ears
Kemonomimi: general, or ambiguous ( means beast )
The usual use of these tropes in Visual Novels is by having them as either a different race, a fantasy creature, or by having them as genetically modified pets. Thus, their personalities usually vary from that of traditional humans and such. There's very few Visual Novels that use this trait currently, however there's been a recent resurgence for the demand, so expect the tradition to rise a little more in the next year or so. As an example, Sekai Project has worked with the creators at NekoWorks to localise their visual novel Nekopara, and even releasing it through Steam ( censored of course ) as well as another translation for a renouned Japanese VN with a huge focus on Kemonomimi, "Pure-Pure!" due to release soon™.
Why Kemonomimi?
There's two major reasons that Kemonomimi is seen as a huge thing for a niche group of consumers. Firstly, catgirls are cute as hell. We can't really deny this. Secondly, is the psychological side of things with building a Kemonomimi relationship, based off an entirely new social construct. Whether you're falling in love with your family pet catgirl, you're helping spirits make peace with humans, or you've saved a stray from the cruel city streets, there's a lot of writing freedom when building relationships in a way that's not usually done. As another psychological point, there's a lot of erotic content in this genre ( at minimum, consistent fan service ). Having this come from a "person" who is psychologically conditioned different is a huge appeal to some people. Having the pack mentality of an animal, or the need to fornicate while on heat, these are different excuses for lewd content than the usual.
Where do I sign up?!
Here's a few examples of existing Visual Novels, with a Kemonomimi theme. ( censored, but still NSFW )
NSFW - http://imgur.com/a/lL8eQ - NSFW
Please tag anything that's NSFW, and link it externally.
Feel free to leave your suggestions on Kemonomimi Visual Novels.
NEXT MONTH'S Theme; dunno, feel free to suggest.
