For the record, can I just state that Alpha-152 isn't listed as one of the playable characters in DOA5? She's referenced in the executable but so are Raidou, Tengu, Genra, and Kasumi Alpha; all characters from DOA Dimensions, which this was originally built on top. There's even references to the stereoscopic 3D of the 3DS. There's a section of code that references character select camera data and all those characters are listed, the only difference is that the newer characters' data here has a different file extension meaning that they're using a newer format for DOA5. The reference to Alpha 152, and the other characters I mentioned, references the older format for these files here. So the list originally posted is accurate minus Alpha 152 and there appear to be 24 total characters in DOA5.
Edit: Okay a little update, I was correct in stating that Alpha-152 doesn't appear to be a playable character in DOA5. However, it does look like she may be making a return appearance as a boss again. If you get a hold of the executable for the demo, search for "_INGAME.cam," which refers to in game camera movement, and you'll get 25 results which includes Alpha-152 but if you search for "_SELECT.cam," which refers to camera movement during character select, then you'll only get 24. Stage names start at 0x00116248 followed by the costumes at 0x00117980. Alpha-152 only has one outfit listed whereas all other playable characters have six and there appear to be three "RTM" models, which are used for unique story mode characters if previous DOA games are anything to go by.