Chapter Text
The sun was high in the sky, bathing the Demon Slayer Corps headquarters in a warm, golden glow. Kyojuro Rengoku, the ever enthusiastic and larger-than-life Flame Hashira, marched through the courtyard with his usual flair. His flaming haori swished dramatically behind him, and his every step was full of energy. But today... something was off.
At first, it was subtle. A slight discomfort in the back of his mouth. Maybe from gritting his teeth during battle? Rengoku, of course, shrugged it off. A little soreness was nothing to a warrior like him. After all, he’d survived countless demon fights and lived to tell the tale. A little toothache? Easy.
But as the hours ticked by, the dull ache turned into a sharp, throbbing pain. By lunchtime, every bite of food was like a small battle of its own. But this time, Rengoku wasn’t winning. His face twisted in discomfort as he tried to chew a simple piece of rice, and he sighed, poking at his meal with his chopsticks like it had personally offended him.
“Ugh, this is ridiculous,” Rengoku muttered to himself, his usual smile faltering. He reached up to rub his jaw, making a mental note that maybe he had overestimated how much pain he could tolerate.
Across the table, Tanjiro, ever the perceptive one, watched closely. He raised an eyebrow, noting the way Rengoku winced after every bite.
“Rengoku-san… are you sure you’re alright?” he asked, voice laced with concern.
“Of course I am, Tanjiro!” Rengoku replied with his usual smile, though it looked a little strained. “Just a little sore from all the fighting. Nothing to worry about.”
Tanjiro wasn’t buying it. He leaned forward, giving Rengoku a look that could only be described as ‘concerned older brother mode.’
“You’re really not fine. You’ve barely eaten anything. If you’re in pain, you should see a doctor.”
Rengoku waved him off with a dramatic flick of his wrist, grinning widely despite the growing ache in his mouth.
“A doctor, you say? I’m fine. A warrior like me doesn’t need to see some mundane doctor just for a little tooth trouble.”
But Tanjiro wasn’t convinced. He could see Rengoku rubbing his jaw with every passing minute, clearly trying to hide how much pain he was in. There was no way he was letting his mentor suffer in silence.
“Please, Rengoku-san,” Tanjiro pressed. “It’s important. We can’t have the Flame Hashira walking around like a walking furnace with a toothache.”
Rengoku gave a dramatic sigh, leaning back in his chair.
“I am the Flame Hashira, Tanjiro. My pain is nothing but a small flicker of fire compared to the flames I battle every day!”
The words were grand, but the pained expression on his face contradicted them. He shoved another bite of rice into his mouth, only to immediately grimace.
Tanjiro raised an eyebrow. “If your fire is burning so bright, it looks like it’s about to explode.”
Zenitsu, who had been sitting next to Tanjiro, overheard the conversation and immediately jumped to his feet with an exaggerated gasp.
“EXACTLY! What if it’s a demon in your teeth?! Maybe a tiny demon trying to attack your gums?!”
Rengoku blinked, slightly confused by Zenitsu’s outburst.
“A demon... in my teeth?” he repeated flatly, staring at Zenitsu like he had lost his mind.
“Yes! What if it’s poisoning your body from the inside?!” Zenitsu flailed his arms around, his face pale with horror. “We could be too late to save you, Rengoku! Think of the people you’re leaving behind!”
“Zenitsu...” Rengoku deadpanned. “I feel as if you’re being a bit dramatic.”
“Me? DRAMATIC?” Zenitsu pointed at his own chest in mock offense. “I’m just trying to protect you, Rengoku! This is a serious dental emergency!”
Rengoku sighed again, rubbing his jaw and looking at Tanjiro.
“Alright, alright. Fine. You’ve made your point. I’ll see a doctor. Later. But it’s just a little toothache. Nothing to worry about.”
Zenitsu immediately grabbed onto his shoulders and shook him.
“No! It’s something to worry about! It could be a giant tooth demon, and you don’t even know it!”
Tanjiro smirked at the two, his face brightening a little.
“I think we’re getting off track here... maybe we should just get Rengoku to a doctor before Zenitsu starts predicting a tooth demon apocalypse.”
Rengoku crossed his arms and looked down at his food again.
“Fine,” he muttered with a touch of exasperation. “You’ve worn me down, you two. I’ll go see a doctor, alright?”
Tanjiro’s eyes softened. “Thank you, Rengoku-san. I know it’s not easy to ask for help, but you don’t have to go through this alone.”
Zenitsu jumped up and started doing a little victory dance. “YES! We saved him! Rengoku won’t die of tooth-related injuries! I’m a hero!”
Rengoku couldn’t help but laugh, though it made his jaw ache even more.
“Zenitsu, I think you’ve misunderstood what’s happening here. But thanks for the enthusiasm.”
As Rengoku stood up to leave, the pain in his jaw flared up again. He grimaced, and this time, his usual boldness slipped away a little more. He wasn’t used to admitting he needed help. He was the strong one, the one who charged headfirst into danger, who fought without hesitation. But right now, a toothache was making him feel helpless in a way he wasn’t accustomed to.
“Well, at least I’ll have some good stories to tell the doctor,” Rengoku muttered with a dry chuckle. “The great Flame Hashira, defeated not by demons... but by a tooth.” He rolled his eyes. “How humiliating.”
“Hey, don’t worry about it!” Zenitsu said cheerfully, completely missing the sarcasm. “We’ll tell the doctor that you’re the bravest man to ever fight off a toothache!”
“I’m sure the doctor will be thrilled to hear that,” Rengoku deadpanned.
Tanjiro shook his head with a warm smile. “You’re a warrior, Rengoku-san, but it’s okay to admit when you need help. Even the strongest people need a little care sometimes.”
Rengoku grinned, though it was a little weaker than usual. “Thanks, Tanjiro. You too, Zenitsu... for... whatever it is you’re doing.”
Zenitsu grinned back, hands on his hips like a proud hero. “Just doing my part!”
Rengoku chuckled and walked toward the door, his hand rubbing his jaw. “Alright, let’s get this over with before Zenitsu starts planning my funeral.”
Rengoku walked out the door, but not to go to the doctor’s. After lunch, Rengoku was supposed to meet up with Giyuu for training. The Flame Hashira was determined to stick to his schedule, toothache be damned. Who needed a doctor when you had a sword to swing? Besides, Giyuu was expecting him, and Rengoku wouldn’t let a little pain ruin his daily routine, no matter how much his jaw protested.
As he walked toward the training grounds, Rengoku couldn’t help but smirk at the thought of Giyuu. The two had a… complicated relationship. Giyuu was always so serious, so composed, completely different from Rengoku’s fiery energy and outgoing personality. But for some reason, they made a good team. Giyuu’s quiet strength and Rengoku’s loud, unrelenting passion balanced each other out, and their training sessions were something Rengoku genuinely looked forward to.
Still, there was something about Giyuu’s stoic nature that always made Rengoku chuckle. The man was so stiff and serious, you could practically hear his brain turning when he was trying to crack a joke. It was a bit of a running joke between them that Giyuu never quite got Rengoku’s enthusiasm, or his humor.
As Rengoku approached the training area, he spotted Giyuu standing off to the side, his katana in hand, his eyes fixed on the horizon. Of course, Giyuu was already there early, always punctual, always serious.
Rengoku grinned as he walked up, his hands behind his head in his usual carefree style.
“Giyuu! My friend! You’re early, as always. I almost thought you might’ve been waiting for me just to see if I’d show up! Did you think I’d be late?”
Giyuu turned his head slightly, the faintest hint of a scowl crossing his face.
“I wasn’t thinking about you at all, Rengoku.” His voice was flat, his tone as calm and collected as ever. “I just like to be prepared. That’s all.”
Rengoku laughed loud enough to echo through the clearing.
“Ah, of course, you weren’t thinking of me. How could I ever doubt that? You're so busy thinking about how perfectly composed you are, you probably forgot to eat lunch, right? I bet you’re starving!”
“I ate,” Giyuu replied simply, though his gaze never wavered. He wasn’t one to admit anything personal easily, but it was clear he didn’t quite know how to respond to Rengoku’s friendly teasing.
Rengoku winked
“Well, that’s a relief. I was beginning to worry you'd only eat once every three days like a wild animal.”
Giyuu’s eyebrow twitched, though his face remained as impassive as ever.
“I’m not an animal, Rengoku.”
“Could've fooled me!” Rengoku teased, giving Giyuu a friendly slap on the back.But as his hand made contact, Rengoku winced slightly. He quickly recovered, giving a casual chuckle, though his eyes betrayed a hint of discomfort
“Ah, maybe I’m getting a little soft in my old age. My bones ache from all the training,” he added with a grin, trying to hide the fact that it was his teeth aching more than anything else.
Giyuu glanced at him, and for the first time, there was the smallest flicker of curiosity in his expression.
“Old age? You’re only 20. And.. Are you okay? You don’t seem like yourself today.”
Rengoku waved him off, his grin widening.
“Oh, I’m fine. Just a little... something, bothering me. Nothing I can’t handle.” He slapped his chest like a warrior ready to charge into battle, but the dull throb in his jaw made it harder to keep up the act. “It’s nothing serious. Trust me, I’m good to go! Let’s train!”
Giyuu didn’t buy it. He was quiet, but not blind (unlike Gyomei-). He studied Rengoku’s face for a moment, his gaze narrowing slightly as he noticed the subtle way Rengoku shifted his jaw, as if trying to hide the pain.
“...Rengoku.” Giyuu’s tone had changed. There was a note of concern buried underneath his usual indifference. “What’s really going on? You can’t hide everything behind that smile of yours.”
Rengoku froze. He had been so used to pushing through pain without saying a word that it took him a moment to process Giyuu’s soft but pointed words. The truth was, Rengoku had never been good at showing weakness, especially not in front of others, and definitely not in front of Giyuu. It wasn’t that he didn’t trust him; it was just that... well, showing vulnerability wasn’t really his style.
Giyuu stood there, waiting for an answer, his posture calm but his expression giving away just enough for Rengoku to know that he wasn’t going to let this go.
“...It’s nothing,” Rengoku finally said with a forced laugh. “Just a little toothache. Nothing to ruin a training session over, right?”
There was a long silence between them as Giyuu studied Rengoku, his face unreadable. Then, with his usual deadpan delivery, Giyuu muttered.
“If it’s nothing, why are you holding your jaw like you’re about to explode?”
Rengoku’s jaw tightened, and he quickly put his hand down, suddenly feeling a little too seen.
“It’s really not a big deal, Giyuu. I’m fine. Let’s train.”
But Giyuu didn’t move. Instead, he raised an eyebrow, not even bothering to mask the amusement creeping into his voice.
“You’re ridiculous. You’re not fooling anyone, you know.”
Rengoku gave him an exaggerated pout, something that could almost be mistaken for childish if anyone else had done it.
“What do you mean? I’m perfectly fine! Just a little sore. No biggie.”
“Right,” Giyuu said dryly, finally taking a step closer. “And I’m not standing here wondering if you’ll collapse from the pain any minute.”
Rengoku shot him a playful glare, though the tiniest bit of frustration seeped through.
“Alright, alright. Maybe I’m not 100% not in pain,” he admitted with a dramatic sigh. “But I don’t need to see a doctor. I can handle it myself.”
“You’ve been talking about this toothache for five minutes,” Giyuu responded, a rare edge to his voice. “I think you should see a doctor. Just get it over with.”
Rengoku blinked, a little taken aback by Giyuu’s unexpected insistence. There was no joking, no sarcasm, just the calm, quiet force of someone who genuinely cared. It hit Rengoku more than he was ready for.
“Fine, fine,” he said with a grin, this time more genuine. “I’ll go see a doctor. Happy now?”
Giyuu gave a small nod, the corners of his mouth almost twitching into the tiniest of smiles. “Very.”
Rengoku laughed loudly.
“You’re impossible, Giyuu. I’ll go see a doctor, but only because you’re making me.” He clapped Giyuu on the shoulder. “Now, let's at least do a little sparring. I can’t let you get too comfortable.”
Giyuu didn’t respond. He just unsheathed his katana, ready to train.
As they squared off, Rengoku couldn’t help but feel a little lighter, despite the pain in his mouth. Giyuu, the quiet, serious man, had just taken the time to look out for him in a way no one else had. Maybe he didn’t say much, but Rengoku appreciated that. And maybe, just maybe, he’d let Giyuu help him with that toothache.
For now, though, there was training to be done.