Too much exposition dump in this chapter, it can be a problem if it does like this in the other chapters, well I'll continue reading it anyways for the oneesans.
I do have to agree that is rather questionable about the girl age and the dragon reason for the attack, but you cannot deny just how amazing the drawings are (that must took a shit ton time to draw all that), dynamic poses and fight scene, and somehow the emotion it convey as well (as was able...
This story has a lot of potential, so much potential that can definitely be a series of a trap going in an adventure with magic system in it's world just like many shonen jump series. Such a shame is a oneshot, much worse that is cancelled.