In hindsight, watching these chapter breakdowns, it's kinda hilarious to realize that in another series, and if he was a bit younger looking (maybe, depends on the manga)...
But Kuroki would totally be the Protagonist.
Just the whole comment on how Kuroki has had three fights with assassins in a row.
Because in a Shonen Manga...well, I could see 'ah, yes, and now you are fighting three separate opponents who are all hyper lethal assassins who each have unique fighting styles and if you screw up even a little you lose horrible, how will you win?!' would totally be the sort of thing you'd see crop up for a Tournament Arc.
It's just that instead of pulling a Heart of the Fist or something and remembering a long lost technique or whatever Ohma was doing every so often, the answer is 'I took the basics, polished them, then polished them again, and kept polishing them, and now I am the Devil Lance and the scariest person in this Arena. Yes, including that guy. I'm still scarier AND I don't have weird personality quirks, just stoic calm.'
Just amusing to realize. Also, ahhhhhhhhhh, I love the Kuroki chapters. Dat Stoic Face of DOOM and all is great. Because all these wacky fighters, and then here comes Kuroki, just calmly striding through all their zaniness and coming out the otherside as The Big Threat.
Edit: Also, I'm sorry, Rei, but your 'oh I just got punched hard enough my descendants will feel it' face is hilarious.