The bridal division puts Seto and Atem on the cover of a magazine, and the world takes it from there.
Asked to describe their relationship in a single word, Atem says quantum state — it cannot be defined until observed, but it unmistakably exists.
The priests, who do not know what a quantum is, coin a word for it that night.
By morning it is the number one trend in two worlds.
This is a translation of an original work on Pixiv.
Original Title: 愛と理論 06 王、量子婚をぶち上げる
Original Author: 葉人(@Hathor_yuki)
Personal site: https://prideshipping.sakura.ne.jp
The trigger was, once again, that magazine with the pink cover.
The words common-law marriage had been printed in it.
"...Seto. We fall under this, don't we?"
"What are you saying at this stage. That's been the case for ages."
"So it is after all! I've finally understood. Reading really does pay off."
"That isn't something to look pleased about. How many volumes have you read?"
But the sight of the King of the Underworld understanding common-law marriage and nodding proudly was seen by someone in Kaiba Corporation's public relations department.
That afternoon, a circular went around the company.
Newly Established Bridal Division — Proposal for Engagement of Advertising Models: President Kaiba, Mr. Atem
"...Who authorized this."
"On the grounds that the president himself judged it optimal."
"I have no such recollection."
"Seto, our love has become a contribution to society at last."
"...Don't expand the meaning as you please."
But the advertising effect was, in fact, projected to be enormous.
In the end, there was nothing to do but judge it optimal.
The moment word got out that the two of them would sit for the shoot, social media exploded on the spot.
The magazine with the pink cover posted the highest sales since its founding, and at length a news bulletin reported the following:
Mr. Seto Kaiba and Mr. Atem: An Ideal Partnership Beyond Common-Law Marriage
In the afterlife and the mortal world both, the voices of celebration would not stop.
Watching the coverage, Atem leaned his head against Seto's arm and said:
"Seto, it appears we're well past domesticity by now."
"...No doubt. It's a social phenomenon already."
The photography studio.
Seto's thinking was more dazzling than the white lighting, and his eye reacted to even a single wrinkle in the backdrop paper.
"The lighting is slack. Drop the angle five degrees. The shadow is half-hearted."
"Y-yes, sir!"
A man who finished the calculations of light faster than the photographer, and settled the composition by pure reasoning.
Seto Kaiba was, by this point, less the subject of the shoot than the director on set.
Beside him, Atem was laughing, thoroughly enjoying himself.
Holding up his ringed hand to the light, he was asking the costume staff things like what civilisation's ornamentation did you take as your reference for this?
"Seto, a natural bearing is what's wanted here, correct?"
"Natural bearing or not, don't deviate from the golden ratio of the composition."
"Which is to say, you derive the natural by theory."
"That understanding is correct."
The staff as one came to a realization.
These two are the type who speak of love through reasoning.
The shoot proceeded with a heat beyond expectation, Seto's minute instructions and Atem's kingly presence overlapping.
The two of them within the frame were, rather than models, the ideal image of a pair itself.
The final phase of the shoot.
The photographer murmured in spite of himself.
"...A little closer, please. So that we feel the love."
Atem looked at Seto's profile and smiled softly.
Without letting his gaze move away, Seto said:
"Love is not something to be felt. It's something to be defined."
"Then shall we continue the experiment in defining it."
The sound of the shutter rang out.
Every last member of the staff was certain that this moment would become the miracle shot to grace the cover.
"The Theory of the Dressing Room. The Equation of Love and the World's Common Sense."
The shoot over and the lighting dropped, the studio was as calm as the stillness after a battlefield.
The dressing room.
Seto undoing his necktie in front of the mirror, and Atem seated on the sofa still in costume, turning the pages of the magazine's proof sheets.
"The image of the ideal partner, it says."
"The definition is far too vague. The ideal is a thing dependent on each individual's measure."
"...But for them, it seems we are that ideal."
"You're joking. Who could serve as your partner."
Atem laughed and tapped his ring lightly.
"Husband and wife as a social concept. In this civilisation they apparently call it a unit of living."
"A unit of living, is it. For a company, it would be something like a merger."
"Which is to say, we're co-managing partners."
"...In effect, yes."
Silence.
Suddenly Atem held out one of the proof sheets toward Seto.
The headline read:
Ideal love is established through the balance of effort and understanding
Seto raised an eyebrow, only slightly.
"Understanding can be derived by theory. But effort is the domain of emotion. That's the troublesome part."
"Seto, you try to handle love by theory."
"That's my method."
"But I handle love as emotion. Which is to say, our love is the compatible type."
Seto let out a faint breath and laughed.
"The establishment of an integrated model, then."
"The Unified Theory of Love. We could submit it to a conference."
The laughter of the two of them dissolved into the quiet dressing room.
Seto glanced at the clock and stood.
"We're going home. Next is the phase of the household as a social experiment."
"And the experimental results appear on tonight's table?"
"If you're the one cooking."
"Then the experiment will succeed. If I take up the knife, you'll help."
The door closed.
The light that remained was the shine of the rings reflected in the mirror.
The compatibility of theory and emotion — that, precisely, was the definition of love the two of them had derived.
A week from the shoot.
One early afternoon, Kaiba Corporation's public relations department was enveloped in a quiet panic.
President, the entire social media trend list is buried under "President Kaiba" right now!
"#IdealMarriedCouple" is number one worldwide! ...Er, that is... they're treating you as a married couple!
From the far side of his desk, signing documents, Seto said one thing.
"And has the share price moved?"
If anything it's trending upward!
"Then there's no problem."
A man who had come to be able to handle economics and romance by the same measure — that was Seto Kaiba.
Meanwhile, around that time, Atem was surrounded by the priests of the afterlife.
"Your Majesty! On the communication devices of the mortal world, the King's marriage announcement is being disseminated!"
"...Announcement? I've announced nothing."
"But! You are recognised as official advertising models equals official married couple!"
"I see, a misunderstanding of civilisation."
Watching the priests carry on, Atem operated a smartphone.
"Is a Like a ritual of blessing in the mortal world?"
"Since it is liked, presumably that is so...! All the afterlife rejoices that His Majesty is receiving blessings!"
"That's a fine thing."
On the finger of Atem, laughing evenly, the ring Seto made shone.
The Kaiba mansion.
A news program's feature was showing on the television.
"The King" and the Modern King: A Love That Crosses Dimensions
Analysis by an economics magazine: what brand effect does the relationship between the two bring?
"The theory of love — is it reproducible? Our feature is up next."
The announcer set out the feature.
"Seto, it appears we've become the subject of a feature."
"Let them do as they like. There's no need to manipulate the information."
"Which is to say, our existence is the proof of the theory."
Seto lifted the corner of his mouth, slightly.
"...Then the next problem is sustainable love."
"A fine phrase. Shall we present it at a conference?"
"Put it in Kaiba Corporation's annual report or somewhere."
Between the two of them, laughter was born again.
However society chose to interpret it, for them the world was always both a "laboratory" and a "daily life."
The rings reflect the lighting, and glitter.
That is not an idol, but the proof of an intersection of theory and affection.
And on this day, the world formally recognised the following:
That love cannot be explained by theory — but if it's Seto Kaiba and Atem, perhaps it can be proven.
The mortal world. The lounge of a hotel on an overseas business trip.
Seto had his laptop open, and Atem was sipping coffee across from him.
Both of them in suits. It should have had every appearance of executives before a meeting, and yet.
Suddenly the press came rushing in.
"President Kaiba! And Mr. Atem! About your relationship, if we could have just a little of your time — !"
"I have never once trusted the qualifier just a little."
"I see, so this is what the mortal world calls an ambush interview."
"President! Since the advertisement, the whole world regards the two of you as the image of the ideal partner — !"
"It isn't a matter of emotion but of compatibility. It's the result of optimisation."
"The ideal is not something sought after, but the collective name for the effort of maintaining it."
"Which is to say, you continue the relationship through effort?"
"Wrong. Your definition of effort is different."
"For us, effort is the continuation of conversation. Love is the process of reaching understanding without avoiding dispute."
The reporter was completely at a loss for words.
Several seconds later, another reporter asked, timidly:
"Th-then... do you love each other?"
"Love is less a matter of definition than of operation. It's in operation now."
"Which is to say, we are in the midst of loving."
The sound of the camera shutters stopped for an instant.
Within that silence, Atem smiled brightly and continued.
"The ritual of the interview isn't bad. But next time I'd recommend making an appointment first."
The press corps was obliged to withdraw in full.
In the afterlife it was no different.
Atem had merely shown his face for a moment and was surrounded.
"Y-Your Majesty... just a little of your time — !"
"Just a little again. Nowhere does anyone learn."
"N-no, in the afterlife too we're running an ideal married couple feature — !"
"There were news programs in the afterlife?"
"We launched one on the spot!"
"I'll grant you the initiative, at least..."
"If you were to express your relationship in a single word?"
"A quantum state."
"...Beg your pardon?"
"It cannot be defined until it is observed. But it unmistakably exists."
The priest was obliged into silence.
That night, in the afterlife, the neologism quantum marriage was born with a bang.
Needless to say, of course, not one of them understands what a quantum is.
Once again in the mortal world.
Back at the Kaiba mansion, he undoes his necktie and takes off his jacket.
"...That was a tiresome stretch of time."
"But it was enjoyable."
"For you."
"The phrase love in theory may get used in the next feature."
"Shall we register it as a trademark."
The laughter of the two of them dissolves into the night view beyond the window.
Even within the storm of coverage, there is no wavering.
Walking the border of reasoning and affection, today again they quietly continued the operation of love.
Early afternoon in the mortal world. Kaiba Corporation head office.
"...Quantum marriage is number one in the trends."
At Isono's words, Seto blinked twice.
On the display, countless tags lined up.
#loveintheory
#operationoflove
#quantummarriage
And a newscaster read out:
"A relationship that cannot be defined until it is observed. This may be called precisely the ideal partnership of the modern age!"
"...Precisely the chaos of the modern age."
"President, requests for comment are flooding in. On the grounds that the advocacy of quantum marriage was the president's own intent..."
"Who advocated any such thing. We were observed without our consent. ...By someone who moves the world."
Just at that moment, there was a knock at the door.
The one who came in was Atem.
The pink magazine (Z — xy) in one hand, he said lightly:
"Did you see? Our quantum marriage is moving the world."
"What's moving it is your statements. I'm on the side that stops them."
"But as a result it's favourable. An age in which love is discussed in theory is thoroughly delightful."
"...Atem, aren't you using delightful and chaotic as synonyms?"
"The difference is a hair's breadth. But if the observer is happy, that's enough."
"Which is to say, if I'm happy, this too is a theory that holds?"
"Naturally. If you are happy, love is at probability one hundred percent."
Seto let out a sigh.
"...Your probability calculations are a bug disguised as romanticism."
"With quanta, indeterminacy is precisely the aesthetic."
Beside them, Isono secretly wiped away a tear. (President... a philosophy beyond marriage at last...)
In the afterlife too, something similar was happening.
"Your Majesty, that quantum marriage is a topic in the afterlife as well!"
"Ah, there was the Nefer-Link."
"By way of Lord Seto's communication network! However..."
The priests spoke with one voice.
"We do not know how one is supposed to celebrate a love that is not observed!"
"You don't have to celebrate it. You only have to sense it."
"To sense it — !"
"Which is to say, His Majesty advocates Sensory Marriage!"
"...Don't generate derivatives as you please."
The mortal world, night. The Kaiba mansion.
"...It seems it's spreading in the afterlife as well."
"Yes, a good tendency."
"I can't call it good. There's even coverage now saying the marriage registration was submitted in a quantum state."
"In fact it hasn't been submitted, but the heart has been observed."
"......"
Silence.
Atem took a mouthful of herbal tea and smiled, looking satisfied.
"Seto. A trend is the aggregate of people's desire to understand. In that case, it's only natural that we, who cannot be understood, should stand at the summit."
"...There's nothing to do but give up."
"On what?"
"On you, and on this phenomenon."
Atem laughed a little and nodded.
"I think that's a wise choice. Love is most stable at the moment it exceeds reasoning."
"...Instability itself is stability, is it."
"That's what quanta are, isn't it?"
Conclusion.
At the centre of the quantum marriage boom that swept the world and the afterlife, the two of them today again quietly loved each other, unobserved.
Night.
A soft light had come down over the living room of the Kaiba mansion.
Atem was seated on the sofa, laughing with the tablet still in his hand.
"Quantum marriage is still number one in the world trends. It seems it's the same in the afterlife."
"Hmph. Far too many people attaching worthless analyses. A marriage that is established if observed, a love whose waveforms have matched..."
Seto, with herbal tea in hand as well, let out a single sigh.
Even so, a very slight softness was mixed into his tone.
"When you get involved, any concept starts to look like a religion."
"And you're one to return an answer like an academic paper, aren't you."
Laughing, Atem traced the rim of Seto's mug with his fingertip.
Seto made a show of turning his gaze aside, and did not try to stop the motion.
"Still, everywhere you look it's a storm of blessing."
"...Let them celebrate as they please."
"Your face looks a little pleased."
"You're imagining it."
Atem let out a small laugh.
That laugh rang comfortably, and for just an instant Seto let the strength go out of his shoulders.
"Seto. In the mortal world, in the afterlife — wherever I am, I'm beside you. I think that's what's natural."
"Naturally."
"Naturally, is it?"
"We are neither the ones being observed nor the ones observing. We merely exist within the same equation."
"Heh... you've become a poet too."
"It's theory."
Seto returned it evenly.
But Atem's smile did not break.
While looking at that calm, Seto's expression loosened as well.
"Here."
Atem lifted his ring lightly.
Seto brought his own ring to meet it, and the two pieces of metal made a small sound.
"This is our definition, isn't it?"
"...Yes."
"Then let's update the definition."
"Update?"
"Not quantum marriage, but determinate marriage."
Atem's voice was like a joke, and serious.
Seto lost his words for just an instant, and in the next moment laughed low.
"When you say it, physics really does weep."
"But you laughed."
"...I'll grant it. Logical destruction."
The two of them laughed together, and just as they were, drew quietly close.
Their fingertips touched, and their temperatures overlapped as though confirming each other.
In the world outside, quantum marriage is making the news.
But this space alone is neither observed nor recorded.
Within a definition that simply, unmistakably exists, the night went on quietly, sweetly.
