>>281967415
I don't see how you can dismiss that part as some "gag". It's clearly meant to depict Denji as like a recovering addict who is finally getting his fix and disregards everything around him in order to let loose all his frustrations on some "bad guys".
Fujimoto even draws a parallel to Yoru and has Nayuta narrate throughout that she ultimately cannot understand Denji or bring out the same kind of "battle lust" as Denji (and Yoru for that matter) are able to.
This is not at all meant to be some gag that doesn't mean anything.