Devil Survivor, Volume 1

What should have been a smiple day out with friends turns into a mysterious disaster when powerful demonic beasts appear. Kazuya and Atsuro were supposed to meet Naoya, their enigmatic friend, but he doesn't show up and intead sends another friend, Yuzu, to meet them and give them specially modded gaming devices. It becomes apparent that Naoya has given them much more than they bargained for when demons spawn from these devices!