User blog comment:Jopjopjop/Volume 20 Spoilers/@comment-26428542-20150612201425/@comment-26428542-20150612205714

It's fine, I think no one really know exactly what it mean until the novel is published. That's what a preview does, making fans speculate or confuse (or both?) but still excited

I already thought about king piece since the explanation of evil pieces. I thought that every high class devils have to go through some kind of ceremonial or ritual where the maou put king piece in each of them and then give them the remaining evil pieces. But to think of it, there is not a single explanation of the trait of the king, so various facts about servants being stronger than their master suddenly make sense (Kuroka, Ise and Kiba)