Makato briefs an infiltration team of JP's agents on their way via train to retake the JP's Nagoya Branch from Ronaldo's control. At the same time, Daichi and Io stow away on the train and ponder why Hibiki left them behind. Just then, they are shocked to receive Hibiki's death clip and resolve to save him themselves since the only people able to receive death clips are friends. In the meantime, the JP's tries to reassess the situation after loosing contact with Hibiki and now their infiltration team as Dr. Kanno repairs the damage to the JP's Osaka servers. Meanwhile in Nagoya, Jungo Torii and Airi Ban plan to infiltrate the JP's Nagoya Branch and retake it from the insurgents, although Airi also speculates that the JP's and the Resistance (Insurgents) had prior knowledge of the calamity. Elsewhere, Daichi and Io arrive in Nagoya to discover a Resistance camp handing out rations to civilians. Just then the camp is attacked by a swarm of rogue Legion demons.
The countdown to extinction begins on Sunday with the arrival of the Septentriones, otherworldly invaders set on the eradication of mankind. Caught in the crossfire, Hibiki Kuze and his friends join in the war for humanity's survival by signing contracts with demons to become "Devil Summoners." Soon, their abilities attract the attention of JP's, an underground agency led by Yamato Houtsuin. Once recruited into JP's, Hibiki and his friends fight and bond alongside other ordinary citizens who are Devil Summoners.
However, with each new day, another Septentrione appears to wreak havoc upon Japan. Even if many lives are lost in the process, before that night ends, the young summoners must defeat the invaders at all costs.
