The main character and his friends, Yuzu Tanikawa and Atsuro Kihara, get caught up in a mess when the main character's cousin sends them a portable device called a COMP and they start to notice demons around the city. Due to the demon outbreak a lockdown was invoked by the Japan Ground Self-Defense Force and now the main character and his friends are trapped in the Yamanote circle of Tokyo with demons they so desperately want to get away from. The leader of any group with COMPs can also see the number of days a person has left to live if they're going to die soon, and mysteriously everyone isolated has a maximum of 7.
Devil Survivor is a strategy role-playing game and is part of the Megaten universe from Atlus. During combat a command system similar to the main Shin Megami Tensei series is used. Devil Survivor also features the trademark demon contract and fusion system the Megaten games are known for and introduces the Demon Auction system to bid for demons in place of the Demon Compendium.