Chapter Text
“If I don’t return within seven business days, assume that I’m dead.”
Without even looking up from the pamphlet in his hand, Megumi grunts. Next to him, Nobara sits, exactly as impassive as her counterpart. Instead of reading, however, she is staring at her nails like they are the most fascinating things in the room. Sure, they might be freshly-lacquered and glossy, but surely not as interesting as what Yuuji has to say?!
“Guuuys, I’m being serious!” Yuuji whines as he sets down the information brochure regarding the S-rank solo quest he’d just picked up from the guild’s receptionist, Miwa.
The pair glance at the piece of paper before shrugging. “This isn’t your first solo S-rank mission, and you always return in one piece. In fact, you take one every other week…” Megumi mutters.
“Yeah, you can’t expect us to throw you a farewell party everytime!” Nobara chimes in.
“Some friends you are,” Yuuji sighs rather dramatically. “Anyway, this one looks crazy. I haven’t seen any quest about the demons in forever.”
“We had one two weeks ago,” Megumi remarks dryly. “And one that you took as quickly as it appeared. What is it with your fascination with all things demon? They’re not all that interesting. And there’s a reason why people don’t rub shoulders with them.”
Yuuji curls his nose in a pout and lets out another whine that doesn’t match his reputation as one of the guild’s few gold-ranking adventurers.
As a half-orc, his magical capabilities are… stunted , to say the least, but he makes up for it in his brute strength, which can rival even their burliest members. His skin is perfectly human, but he has little tusks poking out of his bottom canines that aren’t visible unless you’re really squinting. In fact, his orcish features are extremely subdued, which helps to blend him into the human crowd. Aside from his raw power, lack of magic, and the aforementioned teeth, he has no other obvious features.
Megumi is everything Yuuji isn’t. As a half-demon, he is extremely talented at magic, summoning in particular, and while he dabbles in the occasional weapon-assisted combat, he has zero muscle mass. He’s as lithe as they can get, with a slight purple tint on his otherwise pale skin. There are two short horns protruding out of his forehead and tiny wings hidden under his loose garb.
Nobara is a half-elf with pointy ears and sharp eyes, blessed with clear, supple skin that she prides herself on. Just like Megumi, she is proficient with magic too, although she is more of a long-distance combatant, providing support fire and occasional sniping when needed, using her weapon of a hammer and nails.
As for how the three of them became such a tight-knit squad… Well, that’s a story for another time.
“So, an investigation quest,” Megumi says after glancing at the information brochure. Since demons are magical creatures, it’s imperative that the ones who take on this mission are powerful enough to defend themselves while having a low affinity for magic, thus enabling them to move freely within the realm. Yuuji is the perfect candidate. “Hmm… This route takes you awfully close to the castle.”
“It does! And that’s why I’m so pumped,” says the half-orc while raising his fists. “And why I told you that if I don’t return, I’m dead!”
“Just don’t make any dumb decisions, and you’ll be fine. Oh wait, that’s hard for you to do, Mr. Act-now-think-later,” Nobara interjects.
“You don’t have to be so mean!”
“Let’s go out for dinner today, then. In Yuuji’s honour,” Megumi deadpans.
“Huh?!”
“I can’t believe Yuuji is dead,” Nobara exhales.
“Sometimes I can still hear his voice…” Megumi pinches his brows.
“I’m still alive, guys!” Yuuji grabs his friends and shakes them. The group burst into laughter, which translates to their dinner full of delicious meat and roasted vegetables. One mead turns into too many, and the group finds themselves absolutely smashed. Even though usually Megumi plays the role of an adult, this time he isn’t exempt. Just like his friends, his cheeks are flushed by the end of the night, and he can hardly walk straight.
They walk down the street with Yuuji in the middle, both of his arms around his friends’ shoulders. Loudly, they sing, joining the chorus of their drunken fellows. It’s Friday night, which means there is no shortage of those.
“Your singing is terrible!” Nobara says after a hiccup.
“Like you’re any better? Do you remember that time you tried to serenade, uhhh… Megumi’s cousin, and went so off-key, she cringed?”
“Shut up, shut up!” She glowers, ripping herself away from Yuuji to chase him around Megumi. “She totally loved it, okay? She didn’t cringe! Megumi!”
“She laughed, Nobara. She doesn’t usually do that.”
“That’s a good thing, in’it?! Something, something, the funny guys get the pussies!”
“Who says that?!” Yuuji laughs before tripping over himself, grabbing onto Megumi, and pulling him down. In turn, Nobara falls too, and the three find themselves on a heap.
“At least I get pussies. You guys? There’s no hope for you lot, raging homosexuals!”
“Nobara, you’re a homosexual too!” Yuuji objects while Megumi is there under them, groaning and sounding like he’s about to croak any time now.
With some effort, they managed to untangle themselves and stop Megumi from suffocating to death. It’s a good thing they live in the same lodging, meaning they don’t have to risk falling over in a ditch somewhere.
“I call dibs on the shower!” Nobara raises her hand.
“No way, you always take 3 hours!” Yuuji complains.
“Ladies first.”
Next to her, Megumi shakes his head disapprovingly. “You’re hardly a lady.”
“What’s that, Megumi?! You wanna go?!”
“I agree. Megumi’s more ladylike than you are,” Yuuji nods.
“Oh, that’s it; you both are so dead!”
Their bickering continues into the late hours until they become too exhausted to conjure coherent sentences together, and they pass out on the bed.
—
The continent of Jujutsu is split into two major powers.
One that unites most of the races is the Land of the Sorcerers. Ever since the monarchy’s complete and utter annihilation in the hands of the demons, an organisation called the Sorcerer’s Association took over so as not to plunge the continent into absolute chaos. The associations oversee all political matters, and each branch is reminiscent of a ‘kingdom’, although there is no one crowned as the reigning monarch.
Instead, each branch is assigned a leader, and the area where Yuuji, Nobara, and Megumi live falls under Masamichi Yaga’s jurisdiction. Aiding him in his duties are two platinum-ranked adventurers, Suguru Geto and Gojo Satoru. The latter is hardly ever seen, and somehow no one really bats an eyelash.
The resistance from the remaining noble houses remains a pressure point that must be tightly controlled by the Association, but it’s not something that adventurers like Yuuji are worried about. As long as the land is governed well, they don’t really care who holds the reins.
Beyond the hills, forests, and canyons is an area called the Land of the Curses, inhabited by the demons. While they have been inactive ever since the destruction, their presence never leaves everyone’s minds. How can it, when the outcome of the war is still as evident as it is right now?
And so, this quest that takes Yuuji beyond the Sorcerers’ threshold is not an uncommon occurrence. In fact, there have been more and more popping up because how can someone as battle-hungry as their reigning king be so… passive ?
This long period of inaction after the war is strange. People expected them to finish off the Sorcerers and claim the land as their own, yet even after over a century has passed, there has yet to be any significant attack, aside from the minor stray conflicts caused by the lesser demons here and there. After all, their leader, Ryomen, is known to be a brute. A savage who holds no remorse for murdering and consuming the defeated. The bards sing the tale of four-armed demons with wings twice his size and horns that can cut through steel. They speak about his large maw on his stomach and how the teeth can crunch through the toughest scales and bones.
Every single ballad is no less gruesome than the next, hence Yuuji’s utmost caution when preparing for his trip.
This is supposed to be a quick venture. He’ll spend a day travelling there, perhaps three days for a thorough search, and then another day for his return. So, five days!
He adjusts the satchel containing his supplies as he crosses the boundary. It’s incredible how the air quickly shifts. It’s denser in the demon realm. It smells of magic.
Yuuji swallows his saliva as he quietly surveys his surroundings. A layer of thick mist blankets the forest in front of him, so he takes a dagger and begins to quickly make marks on the roots of the trees as a means of wayfinding.
A couple of hours passed with nothing but silence around him. Occasionally, he’d hear the flapping of wings overhead, but the mist and the tall pine trees thankfully mask his presence. Had someone like Megumi been here, they certainly would have been noticed.
Yuuji makes a face when he finds some oversized bugs flying about, trying to bite his face off. They pose hardly any threat, and he easily kills them.
Another couple of hours, and he can start to see more and more of the land ahead of him. The trees have thinned out, and so has the mist.
Still, he sticks to the shadow. Rushing in would do him no good. While he is confident in his combat skills, the fact that he can’t use magic puts him at a disadvantage.
Everything seems normal so far. No sighting of hordes or anything else that might otherwise seem like they’re preparing for war. There are lesser demons crawling about, but none have spotted him thus far. Most of them are far too happy to bicker and fight amongst themselves.
The sun soon sets over the horizon, and Yuuji takes a break near a lake. He snacks on some nut bars and washes his face before deciding to move again.
He is getting closer to the castle. He’s never seen it in person before, so excuse his excitement.
After another couple of hours, with darkness looming in the sky, he sees it.
A tall, imposing structure sits above a deep, bottomless canyon. It’s massive.
Bats and ravens flock to the structure, built with dark bricks and metal. There’s a sphere of protective barrier surrounding it that warns the castle inhabitants when someone crosses the boundary.
His honey-glazed eyes are wide open as he takes in the hauntingly beautiful sight in front of him. Inside, the demon lord sits. The brutal and cannibalistic Ryomen, who was said to have massacred the kings and queens in cold blood. Just what kind of monstrosity is he, really? Yuuji can imagine a gargoyle-like face with dark grey skin and a deformed nose. He’ll be massive, too! And definitely hunched over. Bald with a lot of sores on his face… And, ugh, definitely disgusting body odour. He probably smells like rotting corpses and fish.
One ugly motherfucker, for sure.
Yuuji shudders at the thought, but that doesn’t stop him from staring a little longer. Ghastly or not, the castle is marvellous.
He has always wanted to be inside one. The ones in the Sorcerers’ realm are in a terrible state of disrepair. Most people choose to steal the bricks and everything else they can scavenge. Once upon a time, they must have been this incredible too.
If he has a choice, he’d love to be a knight of sorts. How good would it feel to fight for a cause he believes in? And if he’s lucky, he might be the one to drive a sword through the demon lord’s heart, thus ending his reign once and for all.
The image of grandeur in his head reduces his spatial awareness. When he eventually comes about, he sees icicles growing from underneath him, freezing his feet and restricting his movements.
Yuuji snaps his head to the side to see a small figure. Dainty and humanoid, but unmistakably demon. The androgynous demon has short, icy white hair with a splash of red around the midsection, and there are two short horns growing underneath their bangs. They wear a traditional garb, and their nails have been elongated into sharp claws meant to tear into flesh.
“You do not belong here,” they say.
Shit, shit, shit.
Yuuji tries to rip his feet off the ground, but the ice is rock solid.
Instinctively, he grabs a shard, and with a strain, he shatters it with his bare hands.
The demon, clearly having not expected it, widens their eyes and summons more icicles from the ground.
This time, Yuuji is prepared. He leaps out of the way, zigzagging his way behind the trees and narrowly avoiding the shards flung his way.
He’s at an obvious disadvantage. Flight is his best option, especially since this demon doesn’t seem like a regular demon. There’s something about them… something that makes Yuuji’s bones tingle in fear. Or maybe it’s just the cold. Who knows?
He avoids yet another icicle, but the flurry continues. With each attack, the air around him grows colder. Steam rises from Yuuji’s mouth as he tries to establish distance between him and the demon but fails.
The demon is quick. They move with such trained precision that they easily keep up with him. An ice wall suddenly grows in front of him, creating a massive wall around the bottleneck.
Just as he draws his fist back to shatter it, his torso is frozen solid.
There’s a blow to the back of his head that makes his vision spin. Then another one that makes everything turn black.
—
Yuuji has always wanted to be inside a castle…
But not like this!
His mouth is tightly bound, as are his arms and legs. Even though he prides himself on his physical strength, he can’t break away from the chains. They must be magically infused or something.
Currently, he’s lying on the ground of a dingy old prison, with drops of water from the ceiling and the ominous glow of the moon peeking from the small cracks in the wall.
When he hears a loud clang, he jumps.
“You’re awake,” they say. A familiar voice from… uh, how long ago was it? “Good. That’ll spare me the effort of carrying your heavy behind.”
“Mmmph!! Mmppphhh!” Yuuji screams through his gag, and all that does is make the demon cringe. Without a care in the world, they grab Yuuji by the arm and undo the bindings with a snap of the fingers.
Yuuji takes that momentary freedom to land a satisfying punch that cracks the demon’s nose before he is promptly frozen solid from the toe right up to his neck.
The demon glowers at Yuuji disapprovingly as they wipe the blood off their nose. That reaction makes his chest puff in pride. Yeah, take that, you demon bastard!
He is roughly shoved and handled out of the underground prison, past a few strange creatures that do not resemble humans at all. All of them produce this strange, rumbly noise from their throats that he can’t understand, but he knows enough to ascertain that these are lesser demons incapable of speech. They must be servants of sorts.
Even without speech, Yuuji can feel them snapping their jaws and staring at him like he’s the freshest piece of meat, all while drooling.
With the gag still in his mouth, he can’t really say anything without sounding ridiculous, so he keeps his peace while trying to find a way out of his predicament.
The interior is just as incredible as its facade, with its marble-crusted surfaces, lush carpets that look damn nice to sink his body in, and tapestries on the wall depicting various gruesome events. There are gargoyle statues scattered along the top of the wall.
Wait, he’s not here to sightsee! Where is this demon taking him? The further and further down the hallway they go, the more luxurious everything seems to be.
No way… No way, no way! Is he being taken to the demon lord? The stinky, fish-eyed, ugly, and… uh, ugly demon lord? Has he said ‘ugly’ yet?
Oh, lord. Is he gonna get eaten or something!?
Yuuji shudders, and his pace slows down, but the demon simply shoves him over and over, forcing him to walk unless he wants to stumble. He needs to get out of here somehow before it’s too late.
Soon enough, he finds himself in front of a large metal gate with remarkable craftsmanship, and he’d wager that he can’t make a dent in it even if he tried. Oh, but he will try.
The doors part with an ominous creak, and it reveals a dark, dimly lit throne room with candelabras along the wall and a tall, black throne with a few animal skulls littered on its base and some on its sides.
The person sitting on it—
Yuuji blushes.
Wait, what?!
No, he’s not blushing! It’s just hypothermia setting in. Probably. No, definitely
This can’t be the demon lord, right? The infamous brute, Ryomen? The stinky bastard that should reek like fishes that have been left in the sun for three days?!
Instead, Yuuji’s imagination is crushed. Shattered to pieces by this man, who is at least three times his size, His skin is perfectly human, if not slightly reddish in hue, and there are two long horns, curved and shaped vaguely like a lightning bolt, protruding from his forehead. His hair is short, and it’s charmingly dark pink in colour, wavy, and slicked back.
One side of his face is covered in what looks like tree bark. Oh, god. He has four eyes.
His eyes go lower as he admires the black geometrical tattoos spread along his massive pecs.
When Ryomen rises, Yuuji can see his massive wings spreading just a little bit, fluttering in mild interest. The line on his rock-hard abs moves, and Yuuji then realises that it’s the second maw. Just as he thinks that, they part a little bit, showing the large molars inside.
Ryomen takes a step forward. His footsteps are heavy, and it almost makes the very ground tremble under his sheer weight.
The man’s eyes, deep maroon in colour zero in on Yuuji, observing him from his toe right up to the tip of his hair, then he glances at his servant with a bemused expression on his face.
“Did this runt do that to you, Uraume?”
“Regrettably so, my lord. It was a lapse in my judgement, and it will not happen again.”
Yuuji takes a deep inhale of breath, not realising that the ice restricting him has thawed. His limbs are red thanks to the cold, and he is numb all over.
“Hmm…” Ryomen stops right in front of Yuuji. Now, Yuuji is not a small man by all means. As a half-orc, he is taller than most. However, he has to look up at this man. Not just a little bit, but he actually has to crane his neck at a significant angle.
Why does he have to be topless? Shouldn’t kings wear fancy robes or something?
“W-what the fuck are you staring at?!” Yuuji snaps. He hates the fact that he has to look up at this man, but staring ahead means ogling the damn chest, so he settles with the lesser evil. Think about fish eyes… Frog eyes… Stinky old men. Ugly. Super ugly!
The too-many-eyes that should unnerve Yuuji, but for some reason, they don't. Bad time to have some weird awakenings.
The mouth on the stomach parts a little more, and a massive tongue peeks out of it. It sends a shiver down Yuuji’s spine. In a bad way. In a totally bad way, okay? No one can convince him otherwise.
“Stop staring at me! I’m not some animal,” Yuuji scowls as he looks down at his own body and realises that he’s no longer bound.
So, he draws a hand back, and with all the force in the world, he swings it towards the demon lord. Uraume flinches next to him, appalled at the audacity, while Ryomen easily catches Yuuji’s full-power black flash with one hand. The impact forces him to take a step back, but he is very much unharmed.
“Feisty,” Ryomen says as he clenches his fingers around Yuuji’s. The gesture isn’t meant to be intimate, he’s certain, but…
His cheeks flare once again.
Oh, he hates his body right now. It’s a good thing that his tanned skin doesn’t make it obvious.
A hand shoots up to his face. Clawed nails painted purple dig into his cheek hard enough for it to be threatening, but not enough to cut.
Ryomen’s throat rumbles inquisitively as he moves Yuuji’s face left and right, like he’s inspecting a new possession. He rips the gag, then the thumb and index finger tighten on Yuuji’s cheeks, forcing his mouth to part.
Ryomen shoves a finger into it, and Yuuji sputters. It’s so fucking big . And his hand runs so damn hot.
The finger pokes the little tusk growing from his bottom teeth, and the king smirks.
It’s so infuriatingly charming in all the demonic ways that Yuuji can’t resist chomping down on it. The taste of copper fills his mouth as he exerts even more power into the bite, threatening to snap that finger right off.
However, Ryomen doesn’t react. He continues to stare at Yuuji with an even wider smirk.
And that only eggs him on. He bites down again and again, but for some reason, the wound doesn’t get any deeper. It’s almost as if he’s…
…Healing himself.
Ryomen pulls his finger out, and there’s not even a trace of blood on it. All he can see is a little scar that soon fades away.
“Fascinating,” he says, his eyes twinkling with mirth. “Take him to the vault.”
“Vault?!” Yuuji asks, incredulous. “Hold on, you can’t just—”
Once again, he is frozen solid. This time, up to his mouth. Just like before, Uraume shoves him forward, and the last expression Yuuji remembers seeing painting Ryomen’s totally not handsome face is a self-satisfied, smug smirk that he wants to kiss, no, wait, punch out of his mouth.
—
The vault… is exactly what it says on the tin.
It’s just a literal vault full of knick-knacks and a mountain of gold the size of a hill. There are trophies, jewellery, gemstones, skulls, weapons, armour, and… everything. It’s just a combination of items that the demon lord has hoarded.
So why is he here?
“Congratulations for being deemed worth enough to be a part of Lord Ryomen’s collection.”
Collection?!
Is he a part of the ‘hoard’? Wait, what the heck? So he’s just about to be left here to rot?
“You think far too loudly,” Uraume glowers, disdain emanating from every inch of their being. “I will not let you die, much to my own dismay. I would prefer that he kill you, if I’m being honest.”
Yuuji’s mmph-mmphing is clearly frustrating Uraume, but they seem like they prefer that over his yapping because they do not release their magic.
“Don’t even think about escaping. It’s useless. We will know if anything comes in and out.”
Fantastic.
Without any further explanation, Uraume turns around and leaves. The moment the door is closed, the ice thaws, and Yuuji does the most sensible thing, which is to try to escape.
The door has no knob, and it’s clearly a pull door, so instead, he tries to punch his way out of the damn vault.
To no avail, of course. He is rewarded with sore knuckles for his efforts.
Stubbornly, he kicks and slams his shoulder against it, but after each fruitless effort, his persistence wavers.
Naturally, he picks up a weapon and starts swinging at the door.
There’s no way he’s going to be trapped here! He needs to go back to Megumi and Nobara, dammit.
Why did Ryomen decide to add him to the vault anyway? He’s not some sort of decoration or collectible. He’s Yuuji! Just a half-orc who is currently very tired and very hungry after hours of hitting the door that stands tall, mocking him.
In the end, he sinks down on one of the velvety cushions and tries to regather his breath. This is ridiculous. This whole thing is ridiculous!
Idly, he toys with one of the many gold coins, and like the petty thing he is, he rubs it on his ass so this definitely ugly demon lord can have stupid stinky coins.
He doesn’t know how long he spends rubbing coins on his ass, but when the door opens the next time, it’s Uraume bearing a plate of food full of meats and vegetables that instantly makes Yuuji’s stomach growl.
“I see that even idiots can learn to save their breath.”
Yuuji would love to take another swing at this infuriating, condescending demon, but he’s exhausted, and that food smells really good.
Uraume puts it at their feet, pushing it towards Yuuji before stepping back and saying, “Lord Ryomen will see you later. Please be on your very best behaviour. It’s in your best interest.”
“Wait, wait, wait!” Yuuji raises his voice, but Uraume ignores him and slams the door shut.
Well, at least the food is good…
—
It’s in the middle of the night that he receives a rude awakening.
He was busy sleeping, dreaming of stuffed roasted chicken and vanilla pudding, when he heard the loud slam of the vault door.
He jumps, his eyes snapping wide open, to see none other than Ryomen standing before him. Under the bright light of the vault, he looks even more handsome—ugly. Ugly!
One doesn’t need to have heard the rumours about him to know that this man wears power like a mantle. Everything he does exudes authority. Even the simple rise and fall of his chest is somehow majestic.
Yuuji’s throat dries a little bit, and he licks his lips.
He hates this feeling.
So he does what he does best when he feels like he’s being cornered. He starts swinging.
Having already expected it, Ryomen easily deflects every single one of Yuuji’s blows before grabbing him by the back of his shirt and lifting him up like he’s some unruly cat instead of a gold-rank adventurer.
“Keep still. You’ll hurt yourself,” he murmurs, his voice tinged with amusement that makes Yuuji hiss. Oh, how he wants to strangle this man! Alas, he doubts both of his hands combined can fully enclose Ryomen’s trunk of a neck.
Okay, but Yuuji really wants to strangle him anyway. Ryomen is talking to him like he’s a pet!
So, he tries to claw Ryomen’s eye out. To no avail, of course. Ryomen easily slaps his hands away with one of his four arms.
“If you behave, I will give you a bedroom to sleep in.”
Oh.
Just like that, Yuuji stills. He stares at Ryomen, blinking his brown eyes owlishly.
“Really?” He asks.
Ryomen hums. “I would hate for my belongings to be… improperly maintained.”
“I’m not your belonging!”
“You are. As are everything and everyone else inside this castle.”
“I’m not anyone’s belonging. I’m Itadori Yuuji, and I will get out of here. Mark my word!”
“Of course you will,” Ryomen coos mockingly as one of his other hands taps him on the cheek the way one would their pet cat. “Very well, then. I will return tomorrow. If you fix your attitude by then and perhaps purr for me, then I will consider moving you to another area.”
“Wait, wait!” Yuuji immediately flails the moment Ryomen sets him down. “Get me out of here! Your gold isn’t very comfortable to sleep on.”
“Oh? You’re going to behave?”
“I didn’t—ugh,” Yuuji groans. Knowing that he has no other choice, he eventually gives in. “Fine! I’ll behave!”
Ryomen chuckles. God, it sounds so damn condescending. “Go on, then. Purr for me, feisty little halfling.”
“I’m not purring for you, you ugly bastard! Freak! Cannibal! Ugly!”
Ryomen rolls all four of his eyes before crossing his arms and putting the other two hands on his hips. He looks so doubly done.
“Suit yourself. I hope you’re prepared to sleep on my uncomfortable gold tonight.”
“Noooo!” Yuuji whines. Anything but that! His back is sore already.
Just one purr, right? All he has to do is just one purr… And then he’ll have a proper bed to sleep on. Just one purr. It’s not that deep, Yuuji. It doesn’t need to mean anything!
He takes a deep breath, stares down at his own feet, and quietly says, “...Meow…”
Ryomen says nothing for a moment.
Unsure, Yuuji looks up to see Ryomen staring down at him with the intensity of a blistering sun. He unfurls his arms and nods. “Uraume. Prepare the guest bedroom.”
The ice magic user, who apparently is standing guard outside the door, bows down and immediately leaves to do as they are told.
Ryomen tilts his head towards the door.
Yuuji stares at Ryomen for a hot second before breaking into a sprint that doesn’t last very long because the king grabs him by the back of his collar once again.
“I hate you,” Yuuji growls.
“I’m sure,” Ryomen replies passive-aggressively as he carries Yuuji outside the vault.
“I rubbed all your coins on my ass, by the way.”
“...Brat.”
Yuuji turns around and sticks his tongue out, but Ryomen simply ignores him.
On his way to the bedroom, he tries to come up with a few different ways to escape his predicament. The castle seems to be tightly guarded, with lesser servants crawling everywhere. Escape routes are far and few since, from what he's seen from the outside, there is only one way in and out.
“Don’t think about escaping, brat. No one comes in and out without my knowledge. And trust me, I know. ”
Okay.
So there’s only one answer.
Yuuji has to kill the demon lord, Ryomen!