From this (see translation of the artbook), we can only get an own interpretation of the story of Xepher, although some things are obvious.
According to many, we could say that the group of heroes from Xepher D are like gods living in a world full of clouds and strange columns as we can see in the video and the artbook.
These gods have powers with respect to time (Orologio, for example, could.. stop the time). In the official pictures we see, in fact, in the bottom left of.. each, some kinds of needles. This is actually their arms or clock hands...