Square Enix isn't really showing the 3DS RPG, Bravely Default: Flying Fairy, at TGS, but the demo it's using to represent the title is pretty impressive regardless. 3DS systems are set up in front of a curved wall with a projected blue background, and a large AR card on the floor.
After paging through some text in the in-game engine (with cute 3D characters designed by Akihiko Yoshida), a young woman appears in an AR view, delivering a monologue in which she pleads for your help before being swallowed up by a crack in the earth.
This is a surprisingly effective bit of AR! The 3DS keeps track of her location, even when you move the camera away, without freaking out or admonishing you as the system's built-in AR games do. She even paces out of camera range herself.
Square Enix wouldn't allow me to photograph my own demo or the stage area, but the AR demo was released on the Japanese eShop, which allowed YouTube user Sumwheat to capture it on video. Should you get the opportunity to play the demo, you'll need a Bravely Default AR card, an image of which can be found after the break.