Board Thread:False Info and Speculative Discussion/@comment-27547895-20160203212624

http://www.ew.com/article/2016/01/08/teen-wolf-the-beast-first-look

Here, Jeff Davis says that it is shadow that creates its form. We know it is at least half werewolf.

So, based on that, I personally think that Oni could very likely be the other half. Currently, they are the only other supernatural creature that is so heavily shadow based.

Just a theory of what could be possible.

Also, it's possible that an Oni was brought back in Kira's test by the writers to remind us they existed, to help us make this conclusion.

Again, just a theory. 