Tokyo is about to collapse and your main weapon to fight back is… a Nintendo DS? Sort of. Devil Survivors use Communication Players (COMPs) which just look like a Nintendo DS to forge pacts with demons. A subtle level of immersion since Devil Survivor is a DS game.
After you befriend demons, like series regulars Jack Frost and Pyro Jack, you can summon them. When you move into battle Devil Survivor looks like this…
… but unlike other strategy RPGs combat switches into a system more akin to a turn based RPG. Fights in Devil Survivor show large enemy sprites and battle animations play over them.
Images courtesy of Atlus.