@veshv I think it's supposed to refer to Kyara, Yakou is going to stand by Kyara's corpse, Baku's exclusive "referee" right from the start even before him.
if only, there is a manga with the same premise but focused more on the restaurant for the killers' aspect, or at least make it a big part. This is just a fantasy mafioso kill'em all which is not bad mind you.