According to a Japanese Shonen Jump scan obtained by Siliconera, it's called Final Fantasy Explorers, and it's a multiplayer action-RPG.
The game will focus on searching for crystals and battling Summons, Monster Hunter-style, in parties of four. Multiple jobs will be available in-game—four of which, the Knight, the Monk, the White Mage, and the Black Mage, are shown on the scan—and taking down Summons will require teamwork and a proper use of class abilities.
The scan doesn't mention a price, a release date, or whether or not Explorers will be coming West.
UPDATE: Square Enix has released the art and screenshots featured in Shonen Jump—you can take a look at those below. They've also confirmed that the game, which is part of the Chrystal Chronicles sub-series, will also have a content-rich single player mode and ad-hoc local multiplayer via wi-fi.
Shonen Jump Scan [Ebitsu]
Final Fantasy Explorers Announced For Nintendo 3DS [Siliconera]
Final Fantasy Explorers Press Release [Square Enix Japan]
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