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.

Liu Yinuo, a 30-year-old ordinary office worker, was accidentally summoned to the game world. To get back to the real world, Liu Yinuo, an excellent game player, began to teach an 18-year-old girl, Tian Enya to play games, who is the savior in the game world. In the end, the two girls finished the goal in the game world with the help of many partners and returned to the real world with a more positive attitude towards life.

Due to family circumstances, Setsuna Kai is moving to a new city where he's supposed to live by himself in an apartment. As soon as Setsuna arrives, he witnesses a mysterious rain of rocks and barely escapes being crushed by an enormous boulder. Setsuna's new home wasn't as lucky, being completely destroyed by another giant boulder. Setsuna is distraught, not knowing what to do when he's approached by a scientist named Hiromi Kaname. Dr. Kaname's equipment apparently can tell that Setsuna is a "Devil Child", and so Dr. Kaname decides to take Setsuna to his laboratory.