A Different Sort of Training (Demon Slayer)

Themes: Genderbending, Rough Sex, Competitive Sex

Summary: In which a Fem!Tanjiro is helped out by a fellow Demon Slayer on her quest to attain mastery over Constant Full Focused Breathing.

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Training. That was pretty much all her life had become, of late. Tanjiro Kamado kneels in the center of the mat and tries her best to focus on nothing but her breathing, her eyes closed and her ample bosom pushing out and then pulling back in, her sizable rack heaving with every breath she takes. Everything had changed for her, recently. She'd met the Pillars, she'd met Kagaya Ubuyashiki.

To say that Tanjiro wanted to one day count herself among their number would be a gross understatement. She WOULD become a Pillar, some day. She would rise up through the ranks of the Demon Slayers, and she would get her sister back, no matter the cost. She would take her revenge on Muzan Kibutsuji for robbing her of her family and to return her little sister her humanity.

But first… training. After all, in the end, demons were monsters that could not always be beaten through raw talent alone. She might have gotten lucky up to this point, but if she was going to one day take down the Upper Demon Moons and Muzan himself, well, Tanjiro knew she needed more. She needed more power, she needed more skill, she needed… more. Just more.

Which was why she was in the midst of her Functional Recovery Training at the moment. She'd just been taught about Full Focus Breathing: Constant by Naho, Sumi, and Kiyo, the young servants of the Butterfly Estate, and now she was trying to learn how to do it at all times, hence the constant part. Breath of Water, the path of Demon Slaying swordsmanship that Tanjiro had found herself on, allowed the user to increase the amount of oxygen in their blood by controlling their breathing.

This then caused the user's strength and agility to increase, allowing them to match even Demons blow for blow. But of course, if you couldn't do the technique constantly, then you were on a timetable any time you went up against a Demon. And while some Demons were over-aggressive idiots who could be goaded into overextending and getting themselves properly killed, many were not.

Many Demons held the intelligence of humans, if they weren't even smarter than that, and if a Demon realized that you were on a clock, well than they would just wait you out and eventually you would die… or worse. That was where Full Focus Breathing: Constant came into play, and why Tanjiro KNEW she had to master the skill. If she could master this skill, then she would be able to do full focus breathing at all times, further increasing her base strength and stamina, as well as her speed.

It was also currently eluding her. Sure, the young swordswoman knew that she wasn't going to learn such a technique in one day. Sure, she knew that it usually took five years of intensive training to become as strong as a Pillar, and she shouldn't expect it to all just be handed to her on a silver platter. Even still… she wanted this so badly. Nay, she NEEDED it.

Letting out a frustrated growl, Tanjiro abruptly opens her eyes, getting off of her knees and standing. Her hands clench into fists as she grits her teeth in frustration, only for a low chuckle to catch her attention and reveal the fact that she currently has an audience watching her. Whipping around, the young woman blinks in surprise at the appearance of another Demon Slayer in the training room with her, watching her, his arms crossed over his chest.

He's not half-bad to look at, is her first thought, and suddenly Tanjiro can't help feeling a bit self-conscious. Despite the scar on her face, Tanjiro is quite the pretty young woman. And she's well aware of it too, especially when the Demon Slayer standing across from her is ogling her up and down quite openly.

Her checkered cloak is really the only concealing bit about her outfit. Her skirt is just short enough that more than a little bit of thigh is revealed despite her stockings, and her latest growth spurt has left her blouse barely able to contain her new breasts.

Averting her gaze, Tanjiro flushes just a bit, visibly embarrassed at the man's observing her.

"A-Ah, sorry… I didn't notice you were there."

"Heh, no, you didn't did you? That's alright, I didn't announce myself. That's on me. What you were working on… that was Constant Full Focus Breathing, wasn't it?"

Tanjiro blinks at that, and brightens up a little, giving the other Demon Slayer a smile.

"You… are you also training in the Breath of Water path?"

Grinning right back at her, he nods and then bows in greeting.

"That I am. Ah, but where are my manners… my name is Yamato Souji. Yours?"

Oh right, exchanging names and what not. God, where were HER manners? One halfway cute boy, and she was tripping all over herself.

"Tanjiro Kamado… it's a pleasure to meet you. But I should probably get back to training now."

Yamato just smiles and nods at her, and Tanjiro prepares to put him out of her mind entirely and focus back on the task at hand. However, before she can resume her kneeling position, he clears his throat, drawing her attention back to him.

"I was actually going to offer you my help… if you wanted it."

That gets her interest piqued. Her head snaps back up and she looks to her fellow Demon Slayer hopefully.

"O-Oh? In what way?"

Grinning, Yamato gives a half shrug.

"Well, as it so happens, I know of a faster way to train in the Constant Full Focus Breathing technique. Rather then trying to get RID of all distractions, what you really need to do is try and learn the technique while dealing with distraction. Obviously, the core trait of Constant Full Focus Breathing is being able to keep it active at all times, even while sleeping, and especially during strenuous activities. Now, what's the most strenuous, distracting activity we can perform without hurting ourselves?"

Tanjiro furrows her brow in thought at that, even bringing a finger to her lips as she contemplates his question. In the end, she can't think of what he might mean, but that's okay because Yamato follows up with an answer for her, an answer that surprises and flusters her just a little bit.

"Sex. In the end, if you can manage to keep your Full Focus Breathing going during sex, then you'll have no problem keeping it up in any other scenario! Makes sense, right?"

It did, actually. It made a lot of sense! And the more Tanjiro thought about it, the more she couldn't see any reason not to give it a try! If this helped her learn Constant Full Focus Breathing faster, than it was one hundred percent worth it, in the end!

"Alright! Let's do it!"

-x-X-x-

And that's how Tanjiro finds herself on her back, laid out atop her checkered cloak, her clothes pulled open. Her tits are hanging out of her fully opened blouse and jacket, and her skirt is flipped up to reveal her panty-less crotch. It wasn't a sexual thing that had Tanjiro going commando… she'd just ran out of underwear in the midst of everything going on, and truth be told, getting new undergarments was so low on her list of priorities that it wasn't even funny.

Still, some part of her is a little embarrassed when Yamato whispers at the sight of her bared crotch. She doesn't have long to focus on the embarrassment though, because he quickly brings his fingers to her pussy lips and starts to work them in and out of her, causing Tanjiro to groan from the sensation. She tries to focus on Constant Full Focus Breathing then, but it's hard, especially with him sawing his digits in and out of her cunt this way and that, getting her worked up and wet for him.

Eventually, the male Demon Slayer pulls his fingers out of Tanjiro's pussy and works open his own pants, dragging his cock out of its confines and into the light. Tanjiro's eyes go wide a little at the sight of it, because in the end it's much bigger than the fingers that were just inside of her. When Yamato brings his cock down on her wet pussy lips, it's a meaty smack that draws a gasp from her, once again disrupting her concentration.

Giving her a knowing grin, the male Demon Slayer winks down at her, even as he reaches back and grabs her ankles, pulling her otherwise limp and sprawling legs up and into the air, and then folding them back so that he has her in a mating press.

"You're going to have to work hard to focus on your breathing while I'm fucking you, Tanjiro. I won't hold back, after all, not even for a moment. If you wanna back out and go back to your previous training, you still can…"

Oh, now he's done it. He's ignited her competitive drive now. Gritting her teeth, Tanjiro shakes her head back and forth.

"N-No! I can handle it… I can handle you. Give me everything you've got!"

And so, he does. Without further ado, Yamato thrusts into her cunt, his cock filling her insides and stretching her out. Needless to say, Tanjiro was a virgin. She'd never had sex before now, it just… hadn't been a thing that had come up. And now here she was, having her virginity taken by a stranger she'd just met. But he was a fellow Demon Slayer at the end of the day, and more than that he followed the Breath of Water too.

So, all in all, it was perfectly okay, right? It was okay that he was thrusting away inside of her like a beast, that he was fucking her with a wild abandon that nearly had Tanjiro's eyes rolling up in her head. It feels so good, so very good, and before she even knows what's happening, the young Demon Slayer is reaching her first climax, groaning as she shakes, and shudders underneath Yamato while being taken in the extremely intimate mating press.

In response, Yamato just laughs a little and then reaches out and grabs her breasts, teasing and molesting her tits as he keeps on fucking her silly.

"Are you even trying, Tanjiro? C'mon, you're supposed to be practicing the technique, not cumming your brains out around my cock like some common whore! Are you a Demon Slayer or aren't you?!"

His needling actually does the trick, his words penetrating the haze of pleasure threatening to fall over her mind. Before she can fully fall into the abyss of pleasure that Yamato's cock is slowly pushing her into, Tanjiro is able to get herself back under control and focus back on the task at hand… Full Focus Breathing. It takes a lot of doing, needless to say, especially with how Yamato doesn't let up for even a second.

In fact, he adds even more to Tanjiro's distractions by leaning down and kissing her, capturing her mouth with his and working his tongue past her lips, where he uses it to wrestle with her tongue. Every fiber of Tanjiro's being wants to just wrap her limbs around his body and forget all about the training… but something deep within her refuses to fall in that manner. If she gives in now, she'll lose all hope of ever becoming a Pillar. She might not even be a Demon Slayer anymore, not truly. If she lets the pleasure swallow her whole, then she might be reduced to little more than a Demon Slayer's concubine.

It's that thought that spurs her on, even as Yamato fucks, teases, molests, and kisses her to his heart's content. Even as her pussy walls continue to clench down and squeeze hard at his cock every once in a while, from an orgasm, Tanjiro is focusing on her technique, focusing on controlling her breathing and reaching that state of Constant Full Focus Breathing.

It's not easy, by any stretch of the imagination. It was never meant to be and having sex while attempting to train in the technique doesn't make it any easier. But in the end, Tanjiro Kamado is a special sort of individual. She's the kind of woman who thrives in the face of adversity, the kind of woman that only goes harder when the going gets rough.

She didn't make it all the way here, she didn't get this far, only to become some toy for a Demon Slayer. She too was a Demon Slayer, and she would prove it, here and now. Of course, her focus gets a little disrupted when Yamato abruptly cums inside of her. That's certainly a shock, having his seed fill her womb to the brim, stuffing her with his ejaculate.

But then he just keeps fucking her, and Tanjiro realizes that he's far more advanced than her, that he's already employing Full Focus Breathing: Constant himself, and that if she wants to be able to keep up with him, then she's going to have to master the technique here and now, or shatter beneath the immense pleasure of his big fat cock.

In the end, Tanjiro Kamado does not shatter. She does not break. It takes hours of being plowed, of being filled with his seed, of being teased and molested by the man atop her, but in the end, Tanjiro achieves her goal of Constant Full Focus Breathing. She doesn't even properly realize she's doing it until Yamato pulls back and looks down at her with an amazed smile.

"You've done it, Tanjiro. You mastered the technique."

With a start, Tanjiro realizes he's right. She's employing Full Focus Breathing constantly now and has been for a good twenty minutes without even thinking about it. She's effectively mastered the technique, reaching higher than anyone would have thought possible in a very short period of time, all thanks to her drive in the face of adversity.

Eyes lighting up in happiness and face splitting into a wide, beaming smile… Tanjiro jumps Yamato. It's her turn to pin him back onto the mat as she flips the tables on the male Demon Slayer without ever letting his cock leave her cunt. Her pussy muscles clench and squeeze down around his throbbing member with a new life to them, as the energy and stamina of Constant Full Focus Breathing thrums through her body, giving her much more power with which to fully explore her sexual awakening.

For his part, Yamato isn't upset at suddenly being the one on the bottom. In fact, he just laughs as he reaches behind her and grabs her by her ass, his hands going up under her skirt, which has flipped back down with the change in position. He takes hold of her buttocks and gives her a raunchy grin before thrusting up into her from below, taking her hard and fast with all his might.

For a second, it's like she's on a bucking bronco, barely able to hold on as she gasps and groans and moans, being bounced up and down on Yamato's cock so haphazardly and swiftly. But she's using the same technique as he is now, and without even having to think about it too. So, in the end, Tanjiro manages to get herself under control, locking her thighs down around his waist and placing her hands on Yamato's chest for support, grabbing him by the shirt and bunching her fists up in it.

Then, she starts returning his upward thrusts with downward bounces, riding him to kingdom cum as she pants and moans and cries out in ecstasy, all while having the biggest grin on her reddened face. They fuck like that for hours more, testing the limits of Tanjiro's new technique, and to her credit, never once does she falter, never once does Full Focus Breathing stop. She truly has mastered the skill, much to her giddy happiness, and she proves it as she rides Yamato through orgasm after orgasm, letting him full her with even more seed, even pulling his face up into her tits and holding his head to her breasts for a good long while.

Eventually, of course, the sun starts to rise, Tanjiro and her fellow Demon Slayer having been training all night long at this point. Though, of course, it stopped being training several hours previous. With a final mutual orgasm for the two of them, they come apart in nonverbal agreement and bring their training session to a close.

By the time they do so, Tanjiro's pussy is so stuffed with cum that her stomach is mightily bloated, the belt she usually wore around her midriff discarded a while before. She looks a little pregnant, truth be told, but Tanjiro doesn't mind as she pulls Yamato into a deep, tongue-filled, passionate kiss. When they pull apart again, she gives him a wide beaming smile and her deepest, most heartfelt gratitude.

"Thank you for your assistance Yamato. Without your help, it would have taken me MUCH longer to figure out Constant Full Focus Breathing."

Yamato chuckles and gives her a nod and a wave of his hand.

"It was no big deal. Happy to help."

Licking her lips, Tanjiro's grin becomes a bit saucier, a bit raunchier, and she steps forward to press herself close to him for a moment. With an excited smile on her lips and a sparkle in her eyes, the female Demon Slayer looks at Yamato somewhat greedily.

"I certainly wouldn't mind doing some more… training with you in the future either."

Yamato's answer is a wide grin of his own, and Tanjiro knows immediately that she and he are going to be seeing a lot more of each other going forward.