Having been left in an unfamiliar world, the boy felt nothing but feelings of rage and betrayal. He vowed to do anything to return to the beautiful scenery of the Spirit Realm. His plan was a simple one. He would harness massive amounts of energy and force open a gateway that would allow him to return. One of the basic laws of the Spirit Realm stated that one who enters may never leave, and one who leaves may never return. This was because the Spirit Realm itself housed massive amounts of energy, and beings that grew strong enough to meet the requirements for ascending gave up much of their physical forms for one that would not be adversely affected by the Spirit Realm's highly charged environment. There was no way in or out to prevent that high energy from having adverse effects on the world around the Spirit Realm.
This is a prettty meaty chapter, huh? I think I did a good job of making the world's history seem interesting, though.
You may have picked up on it already, but there are two kinds of monsters in this world. One that seems like it could be its own thing, and another that seems more like a fusion of different things. If you did not put two and two together, these are the twisted forms of the races the Ryujin Astera, or Shinryu, experimented on. I gave some hints to this before. One of them being the Centaur warrior that disappeared. The Barrier Crusher was what became of him.