The game was revealed in Japanese magazine Famitsu, and pitched as a traditional turn-based RPG.
Details are scarce, but it sounds like you'll play as one of three factions of knights in a land called Ristia. You'll need to manage your squad by tweaking stats and customising their appearance.
"The 2D characters will be animated just like in our action games, and we're also challenging ourselves to build a new type of gameplay by fusing online and offline," said project director Tomohiko Deguchi.
"Most RPGs up to now involve one person or a group of friends playing together, but we're trying to set up this new kind of game, a full-on war that all the users are connected together in. It's a war RPG where not just one player, not just a few people, but all of the players are drawn together as they fight."
Marvelous Entertainment are publishing the game in Japan this summer.