Fighting the Heavy Hitters would Fucking Suck
So earlier today, u/mochaman__ asked "Who is the hardest heavy hitter to actually beat in a fight? And while I was thinking it over, I realized that fighting any of the Heavy Hitters would probably be fucking awful, especially if you encounter them without any prior knowledge of their abilities. Let's run down the list to see what fighting these four in a random encounter would be like, shall we?
Yuta - This guy is literally a 3-phase raid boss. Assuming you survive fighting Yuta and his flying, building sized Pocket Medic that also hits like a truck in pure H2H, you then have to fight him in a domain clash. If you manage to survive the domain clash and finally start to see his absurdly huge HP(CE levels) nearing zero, this fucker refills his ENTIRE bar and now for the next 5 minutes, his giant Shikigami can shoot CE beams, he can bend the sky, create pseudo-domains that cut you up, he himself can send out slashes that cut you up, freeze you in place with his voice, literally see into the future(??), and can disable your Cursed Technique. Yeah, good luck with that.
Hakari - Like Kashimo, you're probably going to waste a lot of time figuring out that Hakari is basically unkillable unless you destroy his brain. But unlike Kashimo, you probably can't use whatever one-shot ability you have(if you even have a one-shot) more than once or twice, so if you didn't manage to kill him during/between Jackpots with said one-shot(and let's be real, you didn't), you're cooked. Oh, and you probably shouldn't even bother with expanding your domain since his is faster, is most likely stronger in a clash, and there's only a very small handful of domains whose sure-hit effects would kill Hakari anyway.
Maki - If you have no idea who Maki is or what her abilities are, you're probably gonna have a really bad time engaging her in H2H only to find out that, not only does she seem to dodge your attacks before you even throw them, but her sword cuts through you like a hot knife through butter, and you also can't seem to heal your wounds with RCT. To make matters even worse, since she has zero CE, you can't sense her movements and you can't trap her, let alone target her, inside your domain.
Yuji - Aside from the facts that Yuji is an absolute monster in H2H, is immune to poison, can reattach his limbs if you cut them off, can throw massive chunks of concrete at you, can explode whatever blood that he spills on your shirt, can completely destroy your connection to your vessel if you're an incarnated sorcerer, and can continually chain Black Flashes, I think the most frustrating part of fighting Yuji is that, no matter how much damage you seem to deal to him, he just never stops fighting.
Despite all of that, Yuji is probably still the least fucked up Heavy Hitter to fight, at least if you don't have any prior knowledge of their abilities. He's fast, hits like a truck, has multiple Innate Techniques, and almost completely ignores pain, but his kit isn't actual bullshit like the other three. He doesn't have a massive Shikigami that heals him, refills his CE, grants him counters to everything you have, and steals your bag mid-fight like Yuta, he isn't literally immortal, nor can he expand his domain over and over again like Hakari, and he can't predict your movements by feeling the minute differences in air pressure, jump through the air or can he slice through you with zero resistance like Maki.
Even so, I know that I still wouldn't want to fight him or any of the other Heavy Hitters. I guess they're called that for a reason, eh?