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Hashira First, Spouses Second: The GiyuShino Low-Key Married AU

Summary:

It's just two weak pillars supporting one another. What difference does it make if they get married?
From the perspective of canon, not much. They are so low-key about the relationship that not even all the other Hashira know about it. Giyuu and Shinobu promised one another to prioritize their demon slaying missions, but that locus of priority can make it difficult to navigate their roles as spouses. What happens with their missions is of no real concern to the other, right? Maybe they both need to talk more, before they find bigger things to argue about than fictional baby names.

This is the chronological version of my somewhat popular Tumblr-based AU, with doodles showing how this sort of lens through which to view canon either makes everything funnier or much more painful. The doodles will be posted here as relevant, but long-time followers of the AU have lots of new material to look forward to.

Notes:

(See the end of the work for other works inspired by this one.)

Chapter 1: Part 1-1: “Hashira, First and Foremost”

Notes:

(See the end of the chapter for notes.)

Chapter Text

‘Giyuu, remember. You are the Water Hashira first and foremost.’

I am not, he retorted in response to Urokodaki’s handwriting.

‘A pillar that supports the Demon Slayer Corp cannot be unstable. Even as your comrades fall around you, you must not be swayed by regret. That is why you must take care of yourself.’


“You’re a Hashira. You have to take care of yourself!”

As Giyuu was turning to leave the hospital, he looked back over his shoulder to Shinobu, the young Insect Breath user who had accessed his injuries and prescribed medicine. She had only stopped in here or there between checking on other patients and training in the Butterfly Mansion dojo.

He replied, “It’s because I’m a Hashira that I have to go.”

She stared back with intensity, the longest Giyuu could remember looking anyone in the eye for a while. “Fine,” she relented. “I understand, my sister would say the same. Just remember to keep the bandages clean and take the full dose of medicine.”

Being let go so quickly made him feel he missed a step. Having overheard her take a stricter tone with other patients, he fully expected she’d speak to him longer than that.

She had a reputation for climbing the ranks quickly, despite her diminutive stature. Maybe if she were a Water Breath user she would be able to cut the heads off of demons, but otherwise, it seemed unlikely for someone of her size. Even with special training from the Flower Hashira, a swordsman like her probably got by on gumption. That was the sort of swordsman not swayed by regret.

Urokodaki did not need to worry about that with Giyuu. Hashira or not, he would not waver. He was accustomed to regret.


“Ara, Tomioka-san was here?” asked Kanae. “I didn’t have a chance to say hello.”

“You don’t have to, Neesan. You’re busy with your own missions.”

“Hashira go on joint missions sometimes, too. I’d like to get along with him. Since we’re all the same age, it’d be nice if he and Shinazugawa-san got along as well.”

“You make it sound like you’re all in a merry little club. I’ll bet Himejima-san would say you’re being distractable.”

“You wouldn’t really get it looking in from the outside. Being a Hashira becomes the core of your being, but there’s more to being human than that.”

“Tomioka-san doesn’t seem to think so.”

“I’m sure there’s more to him than that.”

“Do you like him, Neesan?”

“No, not at all!”

Kanae froze and turned red after blurting an answer out too fast, which was what caught Shinobu’s attention. “You mean, you do like him?”

“No, I meant not like that!”

“Then you don't like him?”

“I don’t dislike him. He’s an important comrade. But the way you asked, it made it sound like asking if I liked him.”

“What difference does that make?” Shinobu grimaced at her.

“There’s a difference! I could like someone, you know.”

She kept grimacing. “…”

“I’m a Hashira, but I’m human, Shinobu. Ever since we were little girls, I dreamed of when we’d both grow up and get married. I still dream about it. Wouldn’t it be nice, Shinobu? To have a confidante, a comfort… your own pillar of support?”

“I don’t need that,” answered Shinobu. She was certain of that, for without knowing it, she felt she already had enough. All the support she needed was the promise she and her sister shared.

Still, the conversation would ring back through her mind at later days and make her feel uneasy. Had Kanae said that because she did not want to be a Hashira anymore? It didn’t seem like her to have such an irresponsible attitude—she took her Hashira duties more seriously than anyone, Shinobu was certain of that. Still, there was a bittersweet fondness in Kanae’s voice when she spoke of brides or Kanao finding a special boy, and a soft sadness in her eyes as they passed by mothers with babies. Kanae had to have known that she could not have it all.

The more signs she saw of it, the more normal it felt. Shinobu paid less and less attention to the hints of Kanae’s yearning. For as much as Kanae mentioned Shinazugawa—her special Hashira-confidante, if it was so special to her to have one—Shinobu sometimes suspected there might be more going on in their friendship than Kanae let on. If there was, she was terrible at hiding it, so maybe it was nothing after all.

Still, Shinobu realized one day, she sort of hoped for Kanae’s sake that there was.

Once Kanae was gone, Shinobu forgot about that hope for years, for all at once, every promise, hope, and dream she ever held for Kanae was dashed.


It only came back to mind the day Shinobu accepted the title of 'Hashira.'

“What is it, Shinobu?”

“No, nothing,” she smilingly replied to her master, Ubuyashiki Kagaya. “I was only thinking of something my sister said once.”

“I would love to hear Kanae’s thoughts, if you don’t mind sharing.”

“She wanted me to give up fighting demons and know the pleasures of being married instead.”

“Did she?”

“It was as she was dying… but she relented, and in her final moments, she told me about the Upper Moon who killed her.”

“Then she gave her consent for you to take the role of a Hashira and avenge her.”

“Essentially. I will do my utmost to live up to her example and fill her role.”

“As much as I would love one, I don’t need another Kanae. I need a Shinobu. You will make a fine Insect Hashira, and I am already very proud of you. I should correct you, though.”

“On what, might I ask?”

“It is indeed possible to be married and to fight demons.”

“Oh, I didn’t mean to say you couldn’t. I am well aware that you and Amane-sama do your utmost.”

His voice sounded like a warm chuckle, though it went on in the usual even keel. “I’m afraid I cannot measure up to your use of a sword, whether I use poison or not. There have been many married Hashira before. One of them even has three wives.”

“Well, yes, but it’s a bit different for a woman. It could take time away from my missions.”

“With the faith I place in you all, I would welcome any of my children’s wishes to have a partner,” he smiled.

“A pillar of support,” she finished with Kanae’s words. “Well, I will take that to heart, but I have my Hashira missions to focus on. As well as the hospital, and my research—I’m really far too busy to even think of such things.”

But, think of it she did.

Only someone who could understand her role as a Hashira would be suitable. She had met most of the other Hashira before. All men, except for her, and almost entirely ineligible anyway—Himejima was out of the question, as were the Sound and Flame Pillars, and there was too much entanglement in the case of Shinazugawa, whom would not be her taste anyway. That left the quiet Water Hashira, always on his own. Perhaps he already had someone? It would be impossible to tell without talking to him more.

At most, he was but a curiosity, and Shinobu always forgot about the question of marriage as quickly as the thought crossed her mind. It too was but a curiosity.


Shinobu, back when she was a Kinoe, left a different impression on Giyuu than before.

“Ara, is that you, Tomioka-san?” she had addressed him.

The voice was familiar. A manner of speech similar to Kanae’s, but not at all her voice. When he turned around, he recognized Shinobu by her eyes. “Kochou?”

“It is! Same as always, all by yourself. Don’t your missions ever get lonely?”

“…” he failed to reply, for he was busy questioning why she had changed so much from the stern, down-to-earth tone she used to take when she was younger.

“It must be busy with so few Hashira. Sooner or later, I’ll be likely to join you. Just a few demons to go.”

“Don’t make it sound so easy.”

“Of course not. I don’t get sent after the easy demons anymore, you know.”

Maybe she lost her mind after losing her sister? Not that he could blame her. He wasn’t much younger than her when he lost his own sister, and he outright wanted to die. Maybe he should say something to express sympathy? After all this time, though, would it be odd? He must have missed his chance.

“Tomioka-san?”

“What?”

“You weren’t saying anything.”

“Should I have?”

“You don’t have to. I was simply making small talk.”

“Then there was nothing to say.”

“It was pleasant conversation. You should try it sometime.”

“I have a mission to get to,” he said and turned away. She had called after him that she’d see him soon, and he advised her to not take it lightly. After all, he felt that the way she imitated Kanae had a mocking tone to it. He couldn’t imagine trying to carry on the image of the dead.

A moment later, he became aware of the texture and weight of his haori, and his stomach twisted.


When he later heard the news that Shinobu was promoted to Insect Hashira, he felt a twinge in his gut that he should apologize. For what, though? For thinking badly of her for a moment? If he had not said anything, then apologizing would be as strange as belatedly expressing condolences about her sister. It wouldn’t mean anything now for a Hashira, for a Hashira could never be swayed by regret.

“Tomioka-san! Not a very long time no see, is it? Now that we’re both Hashira, I’m sure we’ll be seeing more of each other. Let’s get along and do our best.”

“…”

Doing their best was obvious. She really thought lightly of this, didn’t she?

“Tomioka-sa-a-a-n? Hello?”

“Whatever happened to the girl who sternly tended my injuries and prescribed me medicine?”

A look of surprise washed over Shinobu’s face, and for a blessed second, she was quiet. Then she smiled, wider than the tight lips she usually kept on her nowadays placid face. “You remember me from back then?”

“You seemed more serious.”

“You think I’m not serious now?” she sing-songed back to the light and airy voice she used in imitation of her sister. “I’m still very serious. As much about medicine as I am about slaying demons. But I know how to be a human, too.”

“It’s clear you’re not a demon.”

“Oh, a sense of humor. That’s a discovery. You wouldn’t befriend me if I were a demon, would you?”

“Of course not.”

“Wouldn’t that be nicer for everyone, though? It’s my dream to befriend demons.”

“Now you’re poisoning her words.”

“Hmm?”

“You don’t mean any of your sister’s words. Stop playing around if you’re going to honor her memory as a Hashira.”

“Tomioka-san,” she said, but then nothing followed. Giyuu listened for her retort, but when there wasn’t one, he left.


Shinobu was left shaken. Perhaps she had come across too cheeky. Maybe Kanae never sounded as bubbly around the other Hashira as she did while home at the Butterfly Mansion? No, Kanae was certain to be herself anywhere. Even with the bubbly demeanor, Giyuu had a proper understanding of Kanae, and a good dose of respect for her. Shinazugawa and Himejima did too, but it was a surprise to find that from such a quiet colleague. It made Shinobu more and more curious.

“Tomioka-san! Fancy seeing you here!”

“Kochou.”

“Were you on your way to lunch? I just finished my shopping. It takes a while to find all the drug components.”

“I finished.”

“Oh? I see. Maybe I’ll join you next time. What did you eat? Anything good?”

“Simmered salmon and daikon.”

“That does sound tasty. Where?”

“A restaurant.”

“That… is not very conducive to a conversation, Tomioka-san. Or to my lunch.”

“…”

“You aren’t very good at conversation, you know that?”

“You’re talkative.”

“Maybe you’re just cold. Go ahead, Tomioka-san. It’s alright to be human sometimes.”


Perhaps she went to too far, but the next time they met, she assured herself that she was more than right about him. His poor communication got him tied up like a criminal in the middle of the day, after all.

“Look! It’s the guy who murdered that charcoal farming family!”

“He’s got a half-and-half haori, just like they said the suspect was wearing!”

“Ahh! No wonder I thought he was suspicious!”

“No. I’m a demon slayer.”

“Get the ropes!”

For being her senior, he was truly helpless. Since he was stuck, after all, she rubbed in his helplessness with a poke.

“To-mi-o-ka-san~!”

From there, she did the talking, for it was clear he wasn’t handling anything. After getting Giyuu out of that immediate mess, she followed him to where they brought a feverish girl who likely knew something about a demon prowling the area. As it was all a matter of conversational arts, Shinobu later treated the girl and gathered information while Tomioka distracted the hunting dog outside. He was rather useless, she thought, until the girl tried to leave on her own, and he stepped in.

“Why are you going to the mountains alone to avenge someone?” he asked. “Are you hiding something from us?”

The thought hadn’t occurred to Shinobu until he said that. The demon Shinobu had just spoken so roughly of might very well have been that girl’s father. How insensitive—and from someone who always said how she wanted to befriend demons?

Giyuu had always seen through her hollow words better than she thought.


It was a narrow victory, only thanks to how fast Shinobu saved the girl from her own rifle. It wasn’t as if Giyuu didn’t sympathize with the girl’s grief, so he made sure to give her closure on the demon, her father. “His message was likely meant for you: Live.”

He left the bereaved girl with that, but by the ache on Shinobu’s usually placid face, it seemed she felt unsettled. “Tomioka-san…”

“Don’t forget, Kochou. We’re Hashira.”

After a moment of silence, he heard her take a tone bereft of fake cheer. “Yae-san, please bear with your feelings. That’s how we pulled through as well.”

Some of the ire he felt toward Shinobu and her frivolous attitude dissipated. Once again, he chided himself for misjudging her. Her fake cheer and talkativeness must have been how she kept herself from being swayed under the weight of her position. She was a Hashira, first and foremost.


“Tomioka-san, you sure have changed,” she slurped a hot bowl of soba next to him.

Some of the ire came back.

“…How so?”

“Hmm… it’s hard to say. Here I thought you were cold to the bone, but your words… you worried about her in your own way, huh?”

She chewed the mouthful, a bit more than she thought she had slurped off. She peered at him, and even in the low light of the restaurant her eyes had a silvery sheen. She held his eyes a moment before continuing, “You can tell me what you really think. Did something happen that gave you a change of heart?”

It was not a change of heart. He was unwavering and would never have that.

He had very recently had a change of action, though. A judgement he had never made, and he still felt shook that he made that choice. A gamble on that boy was one thing, but betting his whole life on the boy’s sister was an unthinkable matter.

Him? Put faith in a demon?

It was a good thing he was never a true Hashira in the first place, lest his choice smear the Water Hashira position.

And Shinobu? For all her lying, coy words about befriending demons, how would she take such a choice? Her eyes beckoned him on. He had the sense she would listen, and somewhere in his heart, he wanted to tell her. The mission they just finished together gave him a better sense of how seriously she took her new position, though. Telling her such a thing would break her trust, and worse, she could still catch up to that boy and his sister long before they reached Mt. Sagiri.

This new colleague was smart, and if she kept staring at him that way, Giyuu had the feeling she’d stare right into every secret she always tried to pry out of him.

He decided to speak up. “Even if something did happen, my heart will never waver. We are the strongest swordsmen in the Corp, the literal pillars of the demon slayers. This is why we will never forget who we wield our swords for, and who we are protecting. To carry the weight of all this, we Hashira must act as the pillars we are.”


“That’s a befuddling statement,” she concurred. There had to have been more he wasn’t saying, and she wanted badly to know what it was. The more time she spent with Giyuu, the worse he was for her curiosity. “It seems you live a difficult life, but I suppose that’s a good sign.”

Whatever it was it wouldn’t say, Giyuu would not waver or crumble. He was as true a Hashira as Shinobu hoped to be. A pillar of support. A partner. If there was one thing she could tell, it was that Giyuu had no confidante. His lack of conversation skill made that obvious enough, but the way he clumsily hid that something had affected him recently was the reason that stuck out to her more.

“You can tell me—”

“Here’s your simmered salmon and daikon, coming right up!”

Her eyes went to the piping hot bowl set in front of him. “Wow, that looks good!” she remarked. “Tomioka-san, you really like simmered salmon and daikon, don’t you—”

She looked up and saw the face of someone she did not know. It was unnerving how much he looked like Giyuu, yet not. Who in the world over the age of ten had such a childlike innocence in their features? It simply wasn’t right.

“What?”

“No, just… this is the first time I’ve seen you smile, Tomioka-san. Would you mind… can you face the other way, away from me? I’m sorry…”

“………”

It especially wasn’t right on Giyuu.

That face burned its way into her memories, and for the next few days, every time she closed her eyes she saw it again. It made her stomach turn. She thought she might also be gassy too, and made a mental checklist of what ingredients to medicate herself with, but then she heard giggles.

Her own giggles?

Startled, she put her fingers over her lips. Her cheeks flushed, and she had to wonder why. It was only that disturbing sight of Giyuu’s bright-as-sunshine smile burned into her retinas, so why?

Of course! Because she knew something now about Giyuu that no one else did.

It was funny, and she burned with curiosity. Or, possibly heartburn.




2025/05/21 UPDATE: Clearly my most popular fic ever. Thank you all! It is an honor! Some art by me:

2025/10/18 UPDATE: Already another kiriban!! Wow, you shippers all needed this after that movie. Here's more thank-you art from me:

2024/07/27 UPDATE: FANART ALERT!! Thank you so much, Yuki2sksksk, I love it so much!! There are a couple other pieces for upcoming chapters, too. <3 (Please reblog the original Tumblr post here, including the lovely textless version.)

Notes:

Usually when I make a fic for posting on AO3 or an AU to post on Tumblr, it starts with the desire to entertain myself.
This fic, however, started with the desire to apologize.

This AU was never meant to be more than a passing joke at first, so the scattered posts are not well organized. Still, people keep discovering them, and I feel so bad for them with how difficult it must be to follow. Since it has some chronology in my head, it was only fair that I make it more organized. On the other hand, one little tag from someone saying they like it can be very empowering, and I kept myself wanting to please the shippers more and more and more, and hoping that they would like something like this.

However, since I don't write much outright shippy fic, and even when I include any ship material I usually stick to canon ships and focus more on individuals and platonic relationships, that made me feel a bit out of my depth.

So here are your only warnings!

1. There is bed business. However, it is not graphic. I am very happy to post fanart, but I would appreciate it being kept at a teen rating, like the fic is (same goes for any amount of violence to expect).

2. You might notice I chose not to use archive warnings. This is because the AU has, all this time, been very purposefully left open-ended, for reasons you can probably guess. I would rather keep you guessing and happy to fantasize about what direction it could go (until I get to posting that inevitable part of the story, of course).

There is one person who knows, though. Reichel and I have exchanged so many chats and headcanons about this AU that at some parts, it's hard to say where my ideas end and hers begin. She was also a huge help in letting me run details by her, and I'm very grateful. I am also eternally grateful for the chance we had to play games in my apartment until 3am, which resulted in the "High-Key Divorce" parody AU, and running joke that Giyuu and Shinobu are fans of rival baseball teams.

Anyway, you can expect this fic to be around 75K+ words across semi-regular updates, but it won't take long for them to get hitched. Enjoy, shippers!