There's some unused Tengu data present in DOA3's files. It is basically his data from DOA2, partially converted to DOA3's format. (I guess they never got around to finishing it.) Long story short, I now know enough about DOA's .bin file format to be able to fix up some of Tengu's files to get him to a semi-playable state.
It's far from perfect, however. I wasn't able to find the correct properties for all of his attacks (1P and 2F+K, for example, don't act properly against airborne targets), and for some reason I can't enable all of his inputs (P+K and 33F+P won't activate for some reason).
There are also some issues that stem from his files overwriting other characters. Wall-splats and camera angles are hard-coded into the game, which is why you can see some of his attacks have weird camera angles and don't wall-splat properly.
Because of these problems, it is currently unlikely that he will ever reach a fully, properly playable state, unless someone somehow finds a way to select Tengu's actual character ID.
That being said, I still thought this might be interesting to see. It's certainly a far cry from his glitchy, raw data: