When Atem decides to investigate the concept of "everyday life," he reaches a startling conclusion: perhaps true intimacy is not perfection, but the small, imperfect moments people share.
Unfortunately, the rest of the world draws a different conclusion.
A forgotten teacup becomes evidence of cohabitation. A research trip becomes a honeymoon. A handmade ring sparks a cultural movement. Before long, both KaibaCorp and the afterlife have collectively decided that Seto Kaiba and Atem are married, whether they admit it or not.
As rumors spread, new traditions are born, wedding magazines appear in unexpected places, and an entire civilization becomes emotionally invested in two men who insist they are merely conducting research.
A story about domesticity, shared lives, accidental public relations disasters, and the strange way love becomes visible long before anyone bothers to announce it.
This is a translation of an original work on Pixiv.
Original Title: 愛と理論 05 王、生活感を知る
Original Author: 葉人(@Hathor₋yuki)
Personal site: https://prideshipping.sakura.ne.jp
Breakfast. Atem stirred milk into his coffee and asked it with a straight face.
"Who put you up to this one… In dictionary terms, it means an atmosphere rooted in everyday life."
"In other words—something we don't have."
"Don't state that as fact."
"Do we have it?"
"We have daily life, at least."
Seto set down his cup. The sound of it landing felt somehow like a gavel opening proceedings.
"But no one has ever called us seikatsu-kan, have they."
"Obviously. A king and a president radiating everyday ordinariness would undermine the image."
"…It undermines the image?"
"In my PR strategy, at least."
Atem gave a small nod.
"I see. So seikatsu-kan is a risk to one's standing."
"That understanding will do."
"But at the same time—acquiring it might bring us closer to ordinary human relationships."
"…What exactly are you aiming for?"
"Something like a normal couple."
"……"
"What is it, Seto."
"Nothing. A king aiming for normal is quite the spectacle."
A lazy afternoon at Kaiba Corporation.
In the staff cafeteria, the unusual news was already circulating: the president is eating lunch here.
"Did you see that tray… is that homemade again?"
"I heard the president himself called it a royal experiment…"
"Royal? As in, the special advisor…?"
"The King."
"So those two are…"
"At this point, obviously."
While the staff murmured, Seto was eating his salad with perfect composure. His posture was flawless as ever—and yet the chopstick rest was ever so slightly out of place.
"…So this is seikatsu-kan."
Seto murmured it quietly. Atem smiled beside him.
"Hmm… I don't think that's quite it. Jonouchi might know more—should we ask him?"
"Don't. He'd only make it more complicated."
That evening, Seto left for afterlife duty. Behind him, Atem stood holding a small cloth bag.
"What did you bring."
"Leftovers."
"Bringing leftovers to the workplace isn't seikatsu-kan—it's an extension of the bento theory."
"I see. So I still haven't acquired seikatsu-kan."
"At minimum—when every priest in the vicinity is holding their breath, you're nowhere near everyday."
The priests nearby were whispering.
"The King and Seto-sama are sharing… leftovers…!"
"Sacred…!"
"Stop mixing the living world and the afterlife together."
"Seto, I've reached a conclusion."
"You're impatient as ever. Already?"
"Seikatsu-kan is the sharing of imperfect moments."
"Meaning?"
"Chopstick rests slightly off. A jacket left on the sofa. Allowing each other those human margins."
Seto was quiet for a few seconds, then laughed softly.
"Then you already have considerable seikatsu-kan."
"Since when?"
"Yesterday, your cup was left on my desk."
"…That was intentional."
"I see—still at the level of intentional seikatsu-kan, then."
Their laughter dissolved into the quiet room.
The blurry boundary between perfect rationality and everyday life. That was where their daily life breathed.
"…Seto-sama, what would you like to do about this."
Isono held out a tablet. On the screen: the company's internal social network, topped with the post Congratulations on three months of cohabitation, President and King!
"Who posted this."
"Unknown. It was accompanied by a photo of the president's office and the living room tea set."
"……"
"It's entirely a scene from daily life."
"So our seikatsu-kan has been leaked…"
"A large number of staff are celebrating it with great enthusiasm. The comments section is filled with sacred."
Seto pressed his fingers to his temple.
"…Atem."
"What?"
"Do you recall being photographed while making tea?"
"I do. I was told it was a cultural record, so I agreed."
"Who told you?"
"A secretary who comes by often."
"…Betrayal always begins from within."
Meanwhile, in the afterlife, the priests were whispering among themselves before the altar.
"Apparently the King and Seto-sama have officially acknowledged each other as partners."
"Where did you hear that?"
"It's the official announcement from the living world. It says a relationship in which they share their daily lives."
"Isn't that just a mistranslation?"
"No—apparently in their terms, cohabitation equals joint research. In afterlife terms, that's essentially marriage."
"So it's an established fact under afterlife law."
The head priest put his head in his hands.
"…There is no longer anyone who can stop the King."
"Seto, is today an official announcement?"
"No. I'm simply appearing at a new product launch."
"Then why is my name in the materials?"
"…I have no idea."
The two of them took the stage. Cameras flashed from the press. And on the slide—inexplicably—the words: President × King: Ideas Born from Shared Life.
"Who made this slide."
"Probably the design department."
"Betrayal always begins from within."
Questions flew.
"What kind of influence has your shared life had?"
Atem answered immediately.
"I've gained a human flexibility. Particularly, I've learned the importance of seikatsu-kan."
"Wonderful, Your Majesty!"
"…I'm not the King here, I'm a joint researcher."
"But you do share a life together?"
"Theoretically, yes."
"So this is a common-law marriage?"
The room erupted.
Seto exhaled deeply.
That night.
"You look satisfied, Atem."
"The pursuit of seikatsu-kan was a social success as well."
"That's not the point."
"Isn't it? Everyone has officially recognized us. There's no longer any reason to hide it publicly."
"I never had any intention of hiding it…"
Seto sipped his herbal tea and smiled.
"So in the end, seikatsu-kan is something other people find on their own."
"That is theoretically sound—but what they found wasn't seikatsu-kan."
"Difficult."
They set down their cups side by side. In the midst of two perfect silhouettes, just the faintest warmth seeped through.
"What are you planning next?"
"Life optimization with official recognition as a given, I suppose."
"And so another research project begins."
"I simply have no intention of ending it."
Atem laughed quietly.
"Neither do I."
One day.
"…Atem."
"What is it, Seto."
"That thick pink pamphlet—what is it."
"A bridal magazine."
"I know. Why are you reading it."
"We've been officially recognized. So I thought—the next step might be marriage."
Atem was turning pages with a serious expression. The cover read: The Complete Guide to the Perfect Proposal.
"…Where did you get that…"
"Someone in the purchasing department handed it over, said it was for cultural research."
"Cultural research… you were neatly played."
"Seto, this is remarkable. In the living world, this much effort goes into preparing for marriage?"
"The thickness of the paper speaks to the scale of effort."
"It says here, give a ring."
"That's right."
"But in the afterlife, the King's seal has already been conferred. Isn't that a duplication?"
"Before we get to duplication—I have no memory of being given anything by you."
"Then I'll give one now."
"…Don't say things like that so casually."
Atem closed the page and thought seriously.
"A ring is a symbol of a contract, isn't it?"
"Formally, yes."
"Well—we already have a contract. There's the joint research agreement."
"That's not the same as a marriage certificate."
"But the effect is similar. It says valid unless one party wishes to dissolve."
"That's why I said it's not the same."
"Then this is—a legal extension of affection?"
"…Stop reframing it."
Atem, who had acquired back issues and was reading through all of them, and Seto, who kept correcting his understanding—the exchange continued.
At the same time, a murmur was spreading through a corner of the company.
Hey, did you hear? The president and a bridal magazine…
Actually it's the King reading it, apparently.
Which means…?
A wedding? Hosted by Kaiba Corporation…?
Are we already halfway to being a religious organization?
One employee went pale.
P-President—!
"Be quiet. The moment we had an afterlife branch, we crossed that line long ago."
After those ordinary days had passed, Atem arrived at a conclusion.
"I've reached a conclusion."
"Let's hear it."
"Marriage is not a declaration—it's a confirmation of continuation."
"Oh?"
"Which means we're already at that stage."
"Meaning?"
"We are already married. Theoretically."
"I see. Your theory is well-developed."
Atem closed the page and smiled softly.
"Seto, we don't need a ceremony. But let me say just this."
"What."
"Our daily life is the finest ceremony. Every day is the ceremony."
"…I can't argue with that."
A few weeks after the common-law marriage had been declared a fact.
A pink mood had settled over the afterlife.
"…Seto, it's happening again."
"Where this time."
"One of the priests has offered a celebratory prayer."
"What reason did they give."
"We heard that the King has wed."
"Heard from whom."
"We saw the official announcement from Kaiba Corporation."
Seto pressed a hand to his forehead.
"That was the official comment: recognized relationship notice…"
"To them, recognized and married appear to be synonymous."
"A difference in cultural interpretation."
"A mistranslation, then."
"That they respond to it with congratulations rather than correction—that's the power of culture. Well, when the King is the King, perhaps his subjects can't help but…"
The living world was no different from the afterlife.
"Congratulations, President!"
"On what."
"Your marriage…!"
"I am not married."
"But yesterday, we heard you and His Majesty referred to it as the anniversary of your continued cohabitation—"
"I said no such thing."
"The PR department has released the footage!"
"Delete it."
"The afterlife branch has already reposted it!"
Atem sipped his herbal tea beside him and smiled.
"The spread of culture is remarkably swift."
"You don't get to say that."
"Seto, we are now part of a structure that gets celebrated."
"Don't call it a structure."
The pink mood showed no signs of stopping.
"The King has wed!"
"A feast!"
"Scatter flowers before the temple!"
"…And the partner?"
"Kaiba-dono of the living world!"
"Dono?! Is he nobility?!"
"A nobleman of science! It is Seto-sama!"
"Understood, perfectly!"
Every bit of it was a misunderstanding—and yet the festival had already been going for three days and three nights.
Seto's comm device rang.
…Urgent report from the afterlife: "Royal Wedding Celebration Festival, currently in progress."
"Leave it."
"Is that all right?"
"…It's fine. It won't stop regardless."
"Understood. Then in the living world at least—I'll accept the flowers."
Having decided to let both the living world and the afterlife do as they pleased, Seto and Atem sat quietly.
"Seto, this is a ceremony without a ceremony, isn't it…"
"Meaning?"
"The total volume of blessing has exceeded all intent."
"True—there was zero planning involved."
"But the result is perfect."
"…You're enjoying this, aren't you."
"There's no reason to refuse good wishes."
Seto exhaled and placed a hand lightly on Atem's shoulder.
"Let me say it at least."
"What."
"…Congratulations, Atem."
"Congratulations, Seto."
Between them, a quiet air moved through—warm, threaded with laughter.
In the midst of all that pink.
"Atem. To confirm—this is a structural survey of the afterlife's foundational systems."
"I know."
"Not tourism."
"I know."
"I'm going for work."
"I'll accompany you."
"…It looks exactly like a honeymoon."
"That's the observer's problem."
On the day of departure, the press had descended for reasons no one could explain.
"President! Where are you headed?!"
"The afterlife."
"The afterlife?! How romantic!"
"It isn't."
"We understand His Majesty will be accompanying you!"
"He won't. I'm leaving without him."
"Our blessings on the beginning of your journey together!"
"I said it isn't."
Atem laughed quietly beside him.
"It isn't no longer gets through. Social perception has solidified."
"You're the cause."
"You issued the official recognition."
"…Fine, you're coming. Now be quiet. If I leave you here you'll say something unnecessary."
The moment they arrived in the afterlife, the priests scattered flowers.
"Your Majesty, congratulations on your marriage!"
"You're still saying that."
"It says so in the Eternal Edition of a certain bridal magazine!"
"…The Eternal Edition?"
"The special issue of the magazine you made popular."
Seto's brow drew together.
"I merely showed it as part of a cultural exchange."
"The result is that it's treated as a sacred text on matrimony in the afterlife."
"It became a religion."
A priest drew near.
"Our blessings on your journey-research together!"
"Is that a pun on accompany and marriage?"
"The sound works well."
"…Is there nothing I can say to correct any of this."
Seto was gradually making his peace with everything involving Atem.
"Seto, what is a honeymoon, actually?"
"A form of social ritual. A symbol of shared residence following the establishment of marriage." He gave Atem an exasperated look. "You read that magazine front to back and didn't pick that up?"
"So it's a form of public proof of the relationship."
"That's right."
"In that case, this joint survey we're conducting in the afterlife…"
"Absolutely not."
"But the destination is another world. Overnight stay included."
"…No."
"Everyone around us is celebrating."
"No!"
"We're researching together."
"……No. (I want to believe.)"
Atem reached his conclusion quietly.
"Seto, society is something that comes into being the moment it is perceived."
"Don't apply sociology without authorization."
"We have already completed a conceptual honeymoon."
"I don't need conclusions phrased like research papers. If you want an actual honeymoon, I'll take you on one separately."
"That's a promise."
He doesn't want a ceremony but he does want a honeymoon. Seto thought it—but said nothing.
On the desk at the survey base, two notebooks lay side by side.
In the margin of a page, in Atem's hand:
Marriage is a journey of understanding. The destination is always within the other person.
Seto's pen stopped when he saw it.
"…A journey, in the end."
"Yes."
"With no end."
"That's what makes it good."
Their shadows wavered in the lamplight. Beyond the social concept of travel, only one definition remained quietly in that place: walking forward together.
"Your Majesty, the tokens of marriage!"
"…Again."
The priests of the afterlife had gathered in a procession, each bearing a box. Inside: gold, silver, obsidian—rings of every conceivable material, piled in a mountain.
"The craftsmen of the afterlife have poured their very souls into these, for the King…!"
"I'm grateful, but I…"
Seto crossed his arms beside him.
"We don't need them."
"Seto?"
"Those are someone else's ready-made goods."
"Ready-made?"
"A symbol of love made by another's hand looks incomplete to me."
The priests stirred.
Atem looked quietly down at his left hand amid their murmuring.
"Symbols are interesting things, though. In ancient times there was a vein called the vena amoris—the vein of love."
"I know. Believed to run from the left ring finger to the heart."
"The ones who believed it were people who could see love's passage."
"…A romantic way to put it."
"Which means the line from your hand to your heart—runs through me as well."
Seto's breath caught.
"…When we get back, I'll make them."
"Make what?"
"Matching rings."
"Better than the craftsmen of the afterlife?"
"Obviously. Unless it's made by my hands, it has no meaning."
Seto's workshop.
Blueprints overlapped like a double helix.
"The material is platinum. But the structure won't be simple."
The hammer in his hand rang lightly against the metal.
"…Is this the theory of love?"
"Structural mechanics. But the result is the same."
Atem leaned his cheek on his hand and watched quietly from beside him. Each time white light wrapped around the ring of metal, something shifted in his eyes.
"Your hands look cold but feel warm."
"I'm controlling the melting point."
"But that control resembles tenderness."
"Don't theorize it."
"In your hands, matter takes on form. Like a crystal of emotion."
"You've become a poet."
The final polish ended.
Seto let out a quiet breath.
"Done."
"Let me see."
In the light: two small rings.
Simple—with a border like a crown.
On the inside, engraved: Resonance.
Atem received the ring and slipped it onto the ring finger of his left hand.
The moment metal touched skin, a faint heat ran through him.
"…It reached."
"What did?"
"The vena amoris. It reached my heart. Truly."
"That's not a blood vessel."
"Theoretically, no."
Atem smiled.
"But in sensation—it's a fact."
Seto looked away, just slightly self-conscious.
"You really do speak logic and poetry in the same breath."
"You pursue logic to its limit, and I unravel poetry. That's why we resonate."
"…Don't say it like that."
Atem gently slipped the other ring onto Seto's finger.
"With this—your theory now has a circuit of love built in."
"I didn't ask for that function."
"But it's running."
Their fingertips touched, barely.
The pulse running through the vein—as if resonating inside the metal itself.
"…Your Majesty, that—that is—!"
"This?"
The moment Atem held up the ring, every priest drew a sharp breath in unison.
Light reflected from it, and for an instant the air of the afterlife cleared like the interior of a cathedral.
"The King is wearing a ring…!"
"Could it be a sacred implement forged by some god…?"
"No—Seto made it."
That single sentence brought the afterlife to a boil.
"Seto-sama did?!"
"A human?!"
"And DIY?!"
Among the stirring priests, a craftsman-type lit up with shining eyes.
"So you make it yourself. For the one you love, with your own hands…!"
"Exactly. Not a ready-made product—a fusion of theory and passion."
"Theory…!"
"Passion…!"
In no time, DIY marriage had become the new craze in the afterlife. Woodworkers, metalworkers, stonemasons—priests of every craft began spontaneously setting up workshops, declaring:
"Furniture to symbolize my love!"
"Tableware for my beloved!"
"…Your Majesty, how do you intend to take responsibility for this."
An administrator pressed his fingers to his temple.
"Take responsibility? It's a fine trend. Creation is an extension of love."
"Even extensions have limits…"
At Kaiba Corporation.
"…Hey, did you see the news this morning?"
"Apparently the president is wearing a ring."
"Seriously?! With who?!"
"Well—apparently he made it himself."
"DIY?!"
The cafeteria buzzed.
"So the rumor about the president's DIY skills being professional-grade was true."
"That's not the point. The point is who he made it for!"
"That's obvious—the King!"
The air in the cafeteria grew warm.
"The president has finally gone DIY marriage…!"
"Will this make it into the company newsletter?"
"Kaiba Corporation: An Era Where Even Love Can Be Engineered?"
"Stop, that's going to sound like an official tagline!"
Mokuba walked past and sighed.
"Every time my brother makes something, the whole company loses its mind…"
"Well, he is the president."
"And whenever Atem-san's involved, everything tends to become a cultural movement."
"…It's apparently still trending."
"What is."
"In the afterlife, DIY marriage. In the living world, a feature on my craft of love. A cultural achievement."
"Achievement doesn't cover it. The staff were planning a ring-making workshop as a company event."
"The staff are enjoying themselves—that's all that matters."
"You're the cause."
Atem laughed softly.
"But the rings you made have spread love and creation across two worlds."
"…Don't put it in those terms."
"Your logic moved the world."
"…I have nothing more to say."
Seto went quiet. But in that silence, satisfaction and something like embarrassment dissolved into each other.
"Seto."
"What."
"Next—I want you to make a bento box fit for a king."
"…DIY marriage, chapter two."
"An extended theory of love."
"Stop naming things like that."
Their laughter rang out softly in the space between the afterlife and the living world.
"…President, here is a project proposal."
On the large monitor in the meeting room: a slide of flowers and rings.
"Kaiba Bridal Technologies."
"Get to the conclusion."
Seto's eyebrow twitched at the conclusion he could already see coming.
"We would like to build a wedding venue supervised by President Kaiba. The DIY marriage concept has been well-received among staff… this would be an extension of that."
"A wedding venue?"
"Yes. Kaiba Corporation-style. Ring-generation AI, a vow-dome presentation…"
The staff murmured among themselves.
"If the president designs love, that's unstoppable."
"And the King—Atem-san—is already here."
"The brand value would go through the roof."
After a silence, Seto said quietly:
"…From a business perspective, it isn't bad."
And indeed, it wasn't bad from a business perspective.
"So that's an approval?"
"…Approved."
That night.
"Seto, it seems the company has produced another new cultural movement."
"Do you understand? This one is also your fault."
The next morning, an email arrived from the bridal division's PR team.
President, Your Majesty—for the company magazine's DIY Marriage Special Issue interview, we'd love to ask about "the moment of the proposal"…
"Atem. Do you have any memory of such a thing?"
"No. What about from you?"
"No."
Silence.
A brief silence.
"This is a problem… We are technically married, but it appears we're in a state of proposal-never-quite-happened."
"Don't call it never-quite-happened."
"But it's true."
"It's unnecessary. Logically, the relationship is already established."
"But as a matter of culture, something is lacking."
Atem pulled the pink-covered magazine out from under the desk.
"According to this, a proposal is a ritual of putting love into words."
"That's what you do constantly."
"No—it says here, get down on one knee."
"Enough."
That night.
"Seto."
"What."
"I want to integrate my life's OS into your system."
Silence.
"…Is that your proposal?"
"The magazine said choose words that reach the other person's heart."
"They reached. But the meaning was incomprehensible."
"So it was a failure."
"Don't analyze it."
Atem closed the magazine with a straight face.
"I see. So an expression of love must be romantic."
"When you say it, even romance sounds like a research paper."
"What would you do?"
Seto stood up quietly.
"I'll correct your theory."
"Correct it?"
"Love is not construction. It's a choice."
He took Atem's hand and pressed his lips to his fingertips.
"I will keep choosing you. The proposal is always on."
Atem started to say something—then laughed.
"…You really are perfect. An answer no AI could produce."
"Obviously. I'm human."
"Then I'll update myself as well."
"Don't. This means the proposal is no longer never-quite-happened."
"True."
Their laughter intertwined quietly.
The next morning.
President, the bridal division—reservations are flooding in!
In the afterlife, "love is always on" has become a buzzword!
Following DIY marriage—the birth of the Always-On Marriage?!
"Atem… you've created another cultural movement."
"Heh—our love has high productivity."
"Stop saying it like that."
No ceremony. A honeymoon that was technically a business trip. Matching rings made to turn away the priests. A proposal engineered to resolve the never-quite-happened.
And yet—in both the living world and the afterlife, they kept being celebrated.
Interviews, congratulations, bouquets, cakes, and a storm of every happiness to you both.
Seto said, calmly: "Something is wrong. We haven't done anything."
Atem answered, delighted: "A ceremony is the act of celebrating a beginning. Which means our daily life is the very essence of a ceremony."
In the afterlife, the mere sight of the two of them walking hand in hand—symbol of the vena amoris—drew applause from onlookers.
In the living world, a blessing booth, installed by staff without authorization, stood in the lobby of Kaiba Corporation.
Wherever they went, they were celebrated.
Whatever they did, they were celebrated.
And then the two of them realized, quietly:
Even the choice not to have a ceremony had already become a ceremony worthy of celebration.
At night, at Seto's desk.
Layering what they called joint research—the theory of love—Seto murmured softly:
"A ceremony that never ends—that's not so bad."
Atem smiled.
"No. Without swearing to eternity, if there are simply days that go on forever—that's enough."
Celebrated and yet beyond ceremony, the two of them continued.
The world watches still, today—the ongoing ceremony of those who never had one.
