Manga by author Sorano Kairi

The story revolves around high school student Akira Nikaido, a typical slacker living a normal life. That is, until he meets the mysterious Shirogane, a man who suddenly appears and tells him that they have a destiny together. When Akira hears this, he is shocked and doesn't believe a word of it. Aya, a friend of Akira, forgets something in the school one night, and asks Akira to help her and go find it. He agrees, and while there, he gets attacked by a shadow monster. Shirogane convinces him that the balance between the human world and the shadow world has been distorted and that Akira must become a "shin"- a creature of the shadow world- in order to help restore the balance.-wikipedia

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 its 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.