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.