His clothes just barely stand out in the freakshow that is the Heavens Arena competitor intake area. He is eagerly pointed to a line leading to a window where one of the receptionist will give him a form to fill out. 

You know what's harder to do than learning to speak another language by listening to people? Learning to read it without a proper teacher.

He can try to make a guess at the form's contents by familiarity with bureaucracy and studies of street and window signs and discarded newspapers but this is unlikely to make it clear.

He will endure the shame of getting back in line and telling her, "I can't read this."

Several of the people behind him in line will look annoyed but the lady will tell him where to put his age, name, and a signature saying that Heavens arena has no liability what so ever for anything including dyeing in fights and being defenestrated by security.

While Abyssal Fist is struggling with the form one exceptionally young looking entrant explains to his similarly young looking friend that this place is great because you don't have to deal with restrictions like in the Hunter's exam you just fight people and go up when you win.

He's twenty. He puts down 'Abyssal Fist' as his name - he cared enough about that to intimidate a now slightly traumatized librarian into finding synonyms for what his true title is until he found one that seems to flow in this language. He'll sign with just messier version of 'abyssal fist', since they don't use personal stamps here.

That does sound like an advantage. This seems to be closer to the no-restrictions tournaments than anywhere else he's seen. Hunter's exam, huh? That sounds potentially important.

"Abyssal Fist-sama you are #2045 they'll call your name on the first floor of the arena so make sure you remember it. Then please go ahead"
She isn't reading off a script but only because she has it memorized. There is a pretty obvious hallway she vaguely gestures towards.

Sure. Hurry up and wait.

...Actually he nonchalantly lurks in earshot of the kid who mentioned the Hunter's exam.

"Killua Zoldyck-sama you are #2054, Gon Freecss-sama you are #2055 they'll call your name on the first floor of the arena so make sure you remember it. Then please go ahead."
That is enough of a numbers gap that he should get going if he doesn't want to risk missing his fight. At least he got the names though.

Oh well.

He watches the fights leading up to his own, trying to judge how much he should hold back to be good but not absurdly good and hopefully not kill or cripple any of the squishy mortals.

This is actually kind of hard because there are 16 active rings and a huge level of variation since this is before any sort of filtering happens. The median person would lose to a non-cultivator with a few years of martial arts training or a lot of bar fights under their belt. The best person he sees would probably still lose to him in one hit, but is better than the others by enough if he extrapolates out the level of difference he sees in the under an hour of wait time then, well blindly extrapolating is silly but they probably get people actually at his level a few times a year.

Bullshit they do.

...Well. Actually he is pretty early along the path of a martial cultivator. It's not impossible that a mortal could have sufficient training and raw skill to meet him blow for blow if he's not using any techniques. Until they get exhausted after a minute or two of high intensity combat and he doesn't.

His first oppent is a ridiculously generic muscle bound tough guy who takes up what can generously be called a bar-fighting stance.

He holds back his strength and aims blows for places likely to cause pain but not too much damage. He deliberately holds still for a whole second twice, to let telegraphed wide swings catch him in the shoulder and pretend to be knocked off balance a bit by it. He still wins handily after a couple of minutes.

"Ok you can go to the 40th floor."
The referee has a small device of some sort that will print out a little ticket for him.

Just as his fight is ending 2055 is called. His ref has to talk over the crowd commenting on a little kid joining the fray. 

Either the kid is going to get destroyed or do something very impressive. He ought to watch on the chance of the second thing.

The kid takes up a very grounded, but otherwise not that great stance. He then fails to activate any anam or even anything that feels "different but similar" to Warden's cultivator senses. Gon then waits for his opponent to get close and pushes like he is trying to open a door. There is now a person shaped dent in the wall.

The crowd goes wild. The announcer and ref are clearly super impressed but not calling shenanigans. If Warden's hearing is good enough he can find out that the kid is going to floor 50.

Really? No anam at all? Nothing that possibly resembles spiritual energy or some other activation of power?

What about the kid's body, does it look noticeably different to the (stupid worthless tiny) flickers of energy that flow hither and yon all throughout the world?

Kinda, it separately looks like there is something very loosely related to anam latent but not exactly active and if his powers really let him examine flesh itself like the kid's physical muscles are not quite human and in fact are rather more efficient than would be expected at a purely physical level.

He can tell something is different about the boy's body. Without actually touching him and focusing, not more than that.

Maybe he's a local cultivator, whatever that means here. Looks like Heaven's Arena was the right place to go.

He goes to floor 40.

Cool his ticket will let him get an elevator as well as enough money to buy a drink from the vending machines. If he looks at all disappointed at this the staff will reassure him that the floor 40 fights pay out 40,000 Jenny. They will be smart enough to not tell him that this is a decent amount of money for a normal person and  small fortune for a hobo.

There is another line to sign up for fights. He can get in today if he wants, or come back latter if he wants to explore a bit first. If he does now he'll still have some time to observe fights but they'll expect him to stay in bullpen until he gets called.

He kind of needs more money. He'll watch for a little while just in case floor 40 fights are full of cultivators who can pop him like an over-ripe lychee, then sign up for another fight.

Nope, he sees a third kid (what is it with kids here) that is better than a non-cultivator kid should be. But even he is not as stupidly OP as Gon. According to the announcer, the kid is Zushi. Judging by Zushi's fight and the audience reaction it is both the case that Zushi would loose to Warden (unless he is holding back) and that Zushi is considered very strong by the standards of this floor. Everyone else is better than the average on the first floor but firmly in the range of non-cultivator who knows conventional martial arts. 

The audience has a smiling man in glasses who seems to know Zushi. The man has something off about him, but it is hard to tell what given that he isn't doing anything besides watching and occasionally gesturing at Zushi. Zushi goes to talk to him, but Warden gets called to beat up some looser in a gi before he can follow up.

He is not as ridiculously overpowered as he expected to be. That's a sting to his pride, but on the other hand, one does not walk the Path by never being challenged. And strength such as this is a good sign for future advancement. There's a hidden world here, of sorts.

He actually tries, for this fight. Technique to back up his strength and durability - He accepts incoming blows in order to land a disabling punch of his own.

Hopefully not disabling enough to permanently hurt this guy. He's too used to fighting people who recover quickly.

He's not fighting at nearly his hardest, though. Maybe if he utterly dominates, he'll move up faster, but there's no need to rush when he's planning to use the prize money to clean up a bit, and investigate things.

This is great attitude and more or less correct for the nature of this world. Well the hidden power part. The part about moving up faster depending on your margin of victory is only true one floor one, which he'd know if he did even basic research instead of being illiterate and from a world were Heaven's Arena broadcasts aren't staple of sports television programing.  Gi guy is not part of the hidden world and goes down like a sack of potatoes. Warden now has a floor 50 ticket.

He asks the tournament staff for some clarification on how this all works. Can he leave now and come back tomorrow for more fights? How does the pay per fight rise compared to the floor level? What happens if he loses, is he out for good or what?

She seem mildly confused that he doesn't already know this, but not enough to make an issue of it.
In order, yes you can have up to 90 days between fights with no penalty then start running into sanctions for longer breaks. The pay goes up rapidly per floor up till floor 200. A win gets 50,000 J on floor 50, 1,000,000J on 100 and 200,000,000J on 190. Also in tower accommodations are provided for fighters at floor 100+. If he loses he goes down 10 floors. He gets kicked out at the point this would put him bellow ground.  A lot of this changes on floors 200+ but he doesn't need to know more while he's still on 50 (its implied thinking otherwise is arrogant).

Good enough for now! Good enough to go get new clothes and properly wash his sect robes, then sleep in a motel instead of the park and pay a random university student at the library to tutor him for a couple of hours (he's quite quick, and doesn't explain why he's illiterate, and is paying extra for no questions- This ends up being the bulk of what he uses his 40,000 absurdly-small-denomination money for), and then he can stay up all night practicing reading.

And then he goes to floor 50 the next day and wants to fight someone.

This is really stretching 40,000J but a mix of being intimidating to the poor student and thrift stores can make it work. Luckily the written language is extremely straight forward. The script is completely phonetic with limited punctuation and hasn't even had time to go through any serious vowel shits or other changes since it was standardized so he basically just needs to memorize the characters.

His opponent is one of the little kids though he does seem to be the weakest of the three.

"Something's special about you, isn't it?" He asks before the bell rings.

He begins the fight taking it seriously. Something is off about the group. What's this kid's gimmick going to be? Absurd strength in that tiny frame? Some rudimentary form of anam techniques? His fighting style kind of suffers without allies to take advantage while he occupies attention and absorbs blows, but standing firm and punching back while getting the measure of an opponent is one thing he can certainly do.

Zushi is clearly trying not to react to the statement about him being special, but has the acting skill of a 10 year old that has been studying martial arts instead of theater. He opens up with a barrage of punches that are far too strong, fast, and well coordinated for his age but not that much beyond what a non-cultivator adult could manage if by adult you mean "heavyweight boxing champion".

A good fight! Huzzah. He feels a little bad about fighting seriously against a little kid and is noticeably going easy on him, but that goes away the first time a punch sinks into his gut and actually hurts.

Abyssal Fist Warden's style is built to take advantage of his endurance and strength. Full-body maneuvers (with fists and legs both) that open him up to counter-blows but are accordingly difficult to dodge, motions that should be exhausting repeated over and over without noticeable drain. And none of it is overly flashy and inefficient - While not as graceful or practiced as some fighters, his strikes and dodges have very little wasted motion to them.

The judge calls out two points for both of them. There is of course a scoring system that no one bothered to actually explain to him. Luckily sports announcers like stating the obvious and will remind everyone that if either fighter gets to 10 points in absence of a K.O. or similar they win.

He is now taking this fight seriously and wondering how the hell a little kid is this powerful without anam, how does his cultivation work- Feinted leg sweep into straight-arm punch, obvious feint that's actually not a feint at all, push the kid back and space him out by sheer size and willingness to take hits-

Zushi is clearly frustrated, but more like someone being force to hold back then someone actually outmatched.
After being pushed back he willing cedes space to make distance, and takes a hyper grounded stance. He begins to emit something that is very much not anam but is closer than anything else Warden has seen in this world. This is accompanied by a mental pressure that is probably intended as an attack in and of itself.

He is watching very closely. What the hell is this, how does it work- Punch off sheer inertia and combat instincts even as he's mostly paying attention to the not-anam-

The punch gets him another point from the slightly oblivious referee.

In the audience directly behind Warden two newly arrived spectators get an indirect hit from Zushi's attack. This immediately starts a whispered conversion between them.

From the opposite end of the stands, Wing calls out for his student not to use "that".

Zushi will be briefly distracted by his coach before beginning to power down.

Oh, good. The pressure was getting to him a little bit. He smiles a bit with a little nod, trying to say 'no hard feelings' with it.

And: More fighting. That too.

It is close, partially because the scoring system is biased against Warden's counterstriking strategy, but fundamentally this incident really put Zushi in a bad spot. He takes some hits before he gets his head back in the game and with his ranged attack off the table deliberately backing up to the edge of the ring against a taller oppent who was already trying to space him out turns out to pretty crippling.

"Good fight." He bows respectfully. He doesn't seem to be even winded. "I'm sure you'll meet me again soon."

He returns the bow:"Yes, I look forward to earning a rematch when I reach the higher floors"

The two other kids follow Zushi as he goes to talk to Wing. They are stealthy enough to blend into the crowd from perspective of Wing and Zushi, but aren't trying to hide what they are doing from Warden or trying to avoid being tailed themselves.

Wing uses the flawed find a place crowded enough that the crowd isn't listening to each other strategy to secure some privacy for himself and Zushi. At that point he will gently but very firmly remind Zushi that he is not to use "nen" below the 200th floor or for that matter against anyone who isn't either a nen user or trying to actually kill him. 

Warden followed a similar strategy at greater distance, straining his ears.

'Nen', huh? Perhaps he can continue to walk the path after all, once he figures out what Nen is precisely. Floor 200 is the goal.

On to floor 60 for now.

His fight schedule gets slightly desynced from the weird children. As a result it takes till the high hundreds before anyone even remotely challenges him, and they still don't show any signs of actual cultivation. Just martial skill and the weirdly high athletic ability that people from this world can get from intense normal exercise. Increasing prizes plus free housing make Warden's money issues a thing of the past.

His last few fights are attended by a handful of people from floors (fighter rolls are publicly posted). At first glance they appear to have level of life force but if he looks closely he can see that they're life force is unusually well ordered and that they have an extra glow around their eyes while watching the match. In other words they have abilities they are using to watch him, but are hiding their power levels. Unfortunately, they make a point of not sticking around after the match or being available to talk. Also, they seems strangely prone to physical aliments, one is flat out in a wheelchair.

If he does any research into nen, "magic", superpowers ect from public sources he will find... a whole bunch of contradictory BS most of which barely mentions nen. However he will also find out that "magic beasts" unambiguously exist and are typically dealt with by the Hunter's Association. There are some indications that both of these groups use nen, but just as strong indications that magic beasts are perfectly normal animals with usual biology and that the Hunters Association uses technology from the planet CRouton which appears to be from a comic book. So if he wants to know the truth he will need better than public sources.
After a few short months he will finally place onto the 200th floor.

There is an atrium before the "true" 200th floor where a receptionist will explain that at this level there is no more prize money fighter's compete soley for glory (and free luxury accommodations) there is a whole biannual tournament thing with needlessly complex rules if he actually cares but the important thing is not to go more than 90 days without a fight or lose more than 4 fights total.

Destiny awaits, just down the corridor.

Before that-

At around floor 150 he takes a few days' break, and gets a "taxi" or "plane" out to a nice mountain, somewhere isolated. He thinks he's reconstructed the important part of the Twelve Year Sunholder breathing technique. So if he just gets to a place with sufficient purity, and sufficient sunlight-

-Yes, he can, with enough effort, gather up dribs and drabs of Sun anam, sitting on the freezing mountainside and meditating in nothing but boxers. Very little for the effort involved, especially compared to taking pills or drawing from a Treasure or Natural Wonder. But he can gather it. He gratefully cycles the energy towards one of his meridians. He was starting to worry about losing progress or stalling out by taking too long without cultivating.

-And back in the corridor to the 200th floor, he's not looking out for trouble more than his baseline watchfulness.

A motley crew of fighters with very obvious auras will be waiting for him. It roughly seems that the one in the red trashbag mask is the leader, and the clown is separate from the rest be he can seem most of the ones who have come to watch him including the wheelchair guy.

"We know you have something strange going on, but do you actually know how to use 'it'? If you know what we mean then show us your Ten and we'll let you through."

"I'm very strange. 'It' is a mystery to me, beyond the name - Nen. If you wish to see me shroud..."

The Endless Depths defender technique should do nicely. After all, the cold watery immensity of the abyss of Ocean anam is one of the most shrouding things he can imagine. And if they decide to attack, having their blows affect him about as much as the sun bothers the ocean (well, not so much, but confidence is important here) is a bonus. Anam flows and pools around him as the technique forms.

The main group gets visibly confused and starts looking worriedly at their leader.

The clown takes the initiative.

“You weren’t the prey I’m came here for, but thats interesting enough I’ll help you learn.”

He then laughs and throws a Nen infused playing card at Warden.

He's seen this attitude from lower-circle disciples before. Nothing good will happen if he tries to dodge. He lets the card hit his technique, and then - probably - him.

He gives a creepy little grin as the card is negated by the Endless Depths but the real attack it was covering goes straight through. With his newly attached Bungee Gum a flick of the wrist allows Hisoka to forcefully pull Warden over to him. Finally he hits Warden with enough Nen to guarantee he'll awaken (or die) extruding an overpowering aura of malice in the process.

"Hmm, looks like you're smart enough to not try dodging that. I guess I'll take you to your room to recover, but I'll be expecting answers."

The gaggle of randos start to form some sort of objection to all this, but snap to their senses when the aura flair reminds them that they all have pressing appointments with people who aren't Hisoka.

Ow.

His breathing settles into his most-used cycling pattern, out of sheer habit. Perhaps Nen is enough like anam to respond to it. Or if not, at least to his willpower and focus, which is more sharply focused like this.

As Warden starts to concentrate his Nen fully awakens. This takes the form of his life force rapidly exiting his body through millions of microscopic orifices he didn't even know he had, or as non-native possibly didn't have until just now. It is not quite responding the way anam would, but his cycling is doing something. Also, he can now clearly see Nen as something akin to steam rising off of living creature, usually much less rapidly that it is coming off of him.

"Interesting. The conventional advice is to close your eyes, and relax until you can feel the flow then simply picture holding your aura in close to you. Of course, if you want to experiment you have an hour before you're in danger. More if your techniques are partially effective."

Yeah, the Nen is tearing apart his body from the inside out. His body is tougher than an average human's, but not enough to sustain this indefinitely at all.

It's just another kind of cycling. One he has to figure out more or less from first principles while in immense pain. No pressure.

Visualization is more important than breathing techniques? Very well. He attempts various shapes of - willpower, trying to feel out the shape of the Nen, and then trying to influence it. Even a faint waver would be a sign of progress.

Hisoka will give some feedback, but its actually kinda easy for Warden. He'll also explain that it's very common for people to die but this is usually because they don't have the ability to perform complex mental exercises while figuratively bleeding out, or because they don't realize what they should be aiming for fast enough. With Warden's discipline and Hisoka's coaching they shouldn't even get close to the time limit.

He will endure the pain for longer in order to gain more familiarity with this strange 'Nen' energy.

He will also humbly beg his honorable senior for guidance as to the theory and properties of Nen. Kissing up to those stronger than you is an essential skill, really.

"Oh you are shameless, but don't worry I'm known for helping promising young fighters. At some point I'll also want to know more about your strange technique, but for now the basics."

"There are many advanced skills but Ten, Restu, Zetsu, and Hatsu form the core of all Nen use. Ten is what you just learned. Zetsu is shutting down your aura entirely by closing your nodes. It's mostly used for tracking in its pure form, but its energy conservation aspect is used in some of the advanced skill like Ko, which combines all the basic skills. Ren is flaring your aura. By itself it's just a show of strength, but it is folded into many of the advanced techniques. Oh and water divination. Hatsu allows people to develop individual nen abilities. Since I don't know you well enough for my personality test, I guess we'll use water divination."

He gets a glass of water and sticks a leaf on top of it. Then indicates Warden should try Ren on it.