http://shmuplations.com/battlebird/
Battle Bird was a stereoscopic 3D arcade game with a proprietary cabinet, developed by Irem with assistance from their sister/parent company Nanao. Its exact history is quite hazy, as it appears very few cabinets were produced, but this short interview helps shed some light. It doesn’t answer the mystery of “what happened?” (and even Japanese sites and msgboards are mostly in the dark), but it does make for a fascinating look at what could have been.