The latest Shounen Jump has revealed information on 4 antagonist characters in the game.
They are:
Zefiel - the king of the Bern empire. His aim is to take over the continent.
Idoun - Zefiel's close aide who is a shaman (Kitoushi). Details about her are unknown.
(Zefiel and Idoun are the two characters who appear in the background of the boxart).
Bruhnya - One of the three Bern Dragon commanders. A glamorous woman with a domineering personality.
Narshen - One of the three Bern Dragon commanders. He appears to be weak, but he is actually a surprisingly strong general.