This is a continuation of the "Grand Theft Colo" strips from the break between chapters 3 and 4.
The song that is the closest match to what Piroko is singing is Stinkfist by Tool.

Piro speaks:
"...the way that things are gonna be~"
(yes, i know the original Tool song is "the way things have come to be", my version is just what i've always heard :P)

Kimiko's shotgun is a Benelli M4.