'Hello, traveler:
Our blindness allows us to see the future, but it does not allow me to know who you are. Well, I'd like to tell you about our story, so please don't let our existence disappear from this world.
You are in a training base that's set between heaven and hell. It's an unfortunate place, indeed. Challengers come from the heavens to test their strength against the demons. At the same time, the demons tempt those challengers and corrupt them to side with them. The battlefield was set here, right in our homes.
To increase the chance of survival, the archangel, Tyrael, was sent by the heavens to lead our way. While the rogues have learned to use bows, the lancers have learned to use their mana, and the swordsmen have learned to use magic. Just when we thought we could hold our ground, things only got worse for us.