User blog comment:Mnzombie/Issei's Peerage/@comment-213.106.131.123-20131105145946/@comment-1359322-20131106130401

If they could do that Koneko wouldn't have to face near execution, remember Koneko only survived that because Sirzechs pleaded on her behalf, saying that the one at fault is Kuroka not Koneko. And the point here is to merely to say that Issei needs to use 2 Bishop Pieces to revive Kuroka regardless if it's a Mutation Piece or not, since it's a 1-on-1 piece exchange, so Kuroka requires 2 pieces for sure.

And please don't keep saying that the Maous could do something about it, their authority aren't omnipotent, they only took the position of a Maou, something like a Presiden or Prime Minister of a country, the top brass could still force them to step down. Plus the Maous needs to consider the feelings of other Devils too, Issei is related to the Maou, giving him special treatment could received lots of complains from other Devils for being biased.