I noticed something but it might be my imagination. if you remember in the thirteen's dinner they mentioned that one of the thirteen crowns is missing and you can see him in one of the chambers in the lab room, and you can see an envelope in the last panel that says deviculum which is the meeting of high ranking demons that iruma and ameri attended. I think when iruma attends this meeting again it will be for political reasons and showing his worth as a possible candidate for the throne with the other three greats grandchildren, and that's when iruma will meet our antagonist as he'll also be a nominated candidate for the throne in addition to maybe a new nominees chosen by the thirteen crowns. Or at least that's my speculations.
