Siliconera: In addition to Kingdom Hearts: Birth by Sleep and Final Fantasy Agito XIII, Tetsuya Nomura has some top secret projects in the works. That's what he told Famitsu and Siliconera may have a glimpse at one of them.
Square Enix filed a patent application with Tetsuya Nomura as the inventor for a character switching battle system. The patent describes a RPG/action RPG (it mentions both terms) where a player character can switch and control a temporary character during combat. When you jump into the shoes of another character you get his/her/its stats and special abilities. Once time runs out, you automatically switch back to the main character and inherit the temporary character's abilities.