Alliteration's one of my favorite devices, too; in general, I like to try and keep an ear out for how words actually sound, and alliteration is so effective at creating that kind of sound. Am glad the prose style works -- and yes, certainty for those two. Certainty defines those two.
*griiin* Japan can be silly about such things, yes! But Italian culture's such an important part of how the mafia operates, and I like leaving that sense of cultural identity in when I write the Baccano! gang, however much I can do it.
And yes yes YES Vino as Lucifer oh god that's another crossover that should be written.