Found through the source code of Sega’s recently launched TGS 2015 website (confirming Persona 5 at the event), a new game from Vanillaware has possibly been leaked.
The source code for Sega’s Tokyo Game Show 2015 site (currently taken down) had the title “十三機兵防衛圏”, which translates to “Thirteen Mecha-Soldier Defense Zone.” This is the same title that was at the center of Vanillaware’s New Year card in January 2013.
The source code showed “Thirteen Mecha-Soldier Defense Zone” for a PlayStation 4 and PlayStation Vita release.
This is likely related to the new Atlus X Vanillaware game teased for a September 2015 reveal on July 20th, alongside the announcement of Odin Sphere Leifthrasir.
Tokyo Game Show 2015 starts on September 17th and goes until the 20th. Prior to that, SCEJA will have their annual pre-TGS conference on September 15th.
— Game Jouhou via Siliconera