While Namco Bandai hasn’t announced a specific number of playable characters for Project X Zone, we have a little hint. The official blog says, Project X Zone will have over 45 songs and each character will bring their theme into the 3DS game.
Most of the time, Project X Zone pairs characters together for battle scenes, which means the game will pick on theme at random. Use a special attack and Project X Zone switches the music to the song’s hook.
Project X Zone will also incorporate music from Sega, Namco Bandai, and Capcom titles into the game’s field and event scenes. Banpresto is composing original music for Project X Zone like the game’s theme "Mysterious Project" and tracks for the scenario.
Project X Zone is slated for release in Japan sometime this year.