It's called Valkyria Chronicles Duel. You can watch the game's trailer above.
Remember when people used to complain about Sega making Valkyria games for portables instead of consoles? Man, those were the days.
Remember when Japanese game companies used to make console games and not just browser and social games? Man, those were the days.
戦場のヴァルキュリアDUEL PV [YouTube]