Naruse is a new working adult who is exhausted from his unfamiliar life. He reaches his limit and storms into his neighbor's house! There, he finds "that thing" that even makes Naruse addicted to it. A person who knows Naruse says, "He is addicted to birds more than anything else. The person who is addicted to birds is the worst of all..."

Towa became a sweeper admiring the legendary sweeper called, “Orange-Eyed Messiah”. The task of sweeper, which requires to “sweep” the monsters Adys is quite hazardous. On his first real attempt at fighting Adys, Towa encountered Kei, a former sweeper who saved him from being killed. Towa asked Kei to take him as a student. However, not only Kei plainly rejects Towa’s request, he tells Towa that he saw the “Orange-eyed Messiah” die!? An appearance by a mysterious man who seems to be connected to Kei showed up with a grudge from the past. Who is he and what is his relationship with the “Orange-Eyed Messiah”? Will Towa finds out about Kei’s past too?

Luca's friend Will, who is from a lower-class segment of society, has gone missing. Luca's only clue to find his friend is his fondness for a certain club in the entertainment district, where a woman named Yue performs. Will had always said they should go there together sometime. When Luca goes down alone to try to speak to Yue, though, he ends up being beaten badly. Luckily, Yue herself finds him, and takes him to her friend Takaomi to be patched up. It soon becomes clear that Will has fallen victim to a chimera sickness that is becoming common in the lower classes. Luca is determined to find his friend, and to save him.

The world is split into two kinds of people: those on the "inside" of EDEN, and those on the "outside". Within EDEN there is clean air and water - it lived up to it's name of a true paradise. But EDEN cannot contain all of the people of the world. EDEN actually made conditions worse for those outside. Because of this, many resistance groups have been formed. Ricalna Forde is a soldier of the resistance team COSMOS, whose mission is to infiltrate EDEN's main headquarters and destroy the "Central CPU" - that controls all of EDEN.