Here's the first trailer for tri-Ace's 3DS "dungeon RPG" Beyond the Labyrinth:

It turns out that the girl actually isn't the main character. She's the main character's companion. The main character appears to be you -- the player. Your goal is to reach the exit on the top floor of labyrinth. The girl accompanies you. 
 
The genre for Beyond the Labyrinth is "3D Dungeon RPG." As you explore the dungeon, the lower screen draws out a map for you. 
 
You'll encounter enemies along the way. Run into an enemy -- they're visible in advance -- and the game will switch to battle mode. The battle system is a bit mysterious at present, but it seems as though you can have four members in your party.

It's releasing on January 15th in Japan. (¥5,800)

You can throw stones as weapons only upon beginning the game, but as you progress you'll gain extra abilities.

The main character is controlled by you, but on occasion she'll lead and you'll have to follow.

Your aim is to get to the dungeon's exit. The game's battle component involves facing off against the creatures that roam the dungeon.

That's some nice boxart

The game's music sounds cool:

http://www.youtube.com/watch?v=8Q6jFABqlfM&feature=BFa&list=PL89C04823A1C83A21

The game's limited edition in Japan includes an Augmented Reality 2012 calender.