After discovering the concept of dating, Atem decides it should be studied properly.
What follows is a series of experiments: luxury dates that feel like diplomatic summits, romantic walks that turn into card shop visits, cooking disasters, movie nights, and increasingly questionable research into love itself.
Meanwhile, the boundary between the living world and the afterlife grows thinner. As Kaiba and Atem continue building a life together, the question is no longer whether Atem can return to the afterlife—but whether he still wants to.
A story about dates, doorways, and the quiet realization that home can become a person.
This is a translation of an original work on Pixiv.
Original Title: 愛と理論 02 王、デートをする
Original Author: 葉人(@Hathor₋yuki)
Personal site: https://prideshipping.sakura.ne.jp
Over morning coffee, Atem said this with a completely straight face. His phone was warm from too much scrolling—he'd apparently been studying all night. Seto recalled him rustling around in the early hours and thought, so he never slept.
"…Did you dig up another strange paper?"
"No. It says it's an important ritual in the romantic life of the living world. To deepen mutual understanding and build emotional intimacy."
"In other words, an excuse to share free time."
"That's logical. But I want to try it myself."
Seto set down his cup and narrowed his eyes, just slightly.
"The king of the afterlife wants to conduct fieldwork in civilian culture."
"It's part of my research. With you, of course."
"A date for research purposes. I'm honored."
That light exchange led, somehow, to the day of their first date. Atem had made the mistake of saying leave the plans to you—and a few hours later found himself in the top-floor lounge of a Kaiba Corporation luxury hotel. Reserved exclusively, naturally. Dedicated staff from the entrance, a black limousine at the drop-off.
"…This is less a romantic outing and more a diplomatic reception, isn't it?"
"A king's outings require appropriate treatment."
"That's not quite what I meant."
The scent of herbal tea rose between them. Atem held his cup and spoke with half-lidded eyes.
"You arrange everything perfectly. Which means this date is missing its essence—the experience of fumbling through things together."
"You'd call sacrificing efficiency romance?"
"…Apparently so."
Seto gave a quiet laugh.
"Then romance is the defeat of rationality."
"But it's not a bad defeat."
"…That's a surprisingly human thing to say."
"Becoming human is your fault."
Silence.
In that brief pause, their eyes met—and neither looked away. Beneath the layers of logic and banter, something soft and warm was there.
"Next time," Atem smiled, "I choose where we go."
"Where?"
"A park. We walk together, buy something, and do whatever you'd consider inefficient."
"…For example?"
"Sit on a bench. Do nothing."
Seto laughed along and nodded.
Time with no need for strategy, rationality, or victory.
Having someone to share that with was, it turned out, a greater happiness than expected.
A sunny afternoon.
Atem had changed out of his sleep clothes into a light jacket.
"Today's date is my plan."
"Let's hear it. What's the research content?"
"Walk together, share discoveries. A simple observational date."
Seto raised an eyebrow.
"So—a walk."
"Academically, yes. But in the living world it's classified as a romantic act."
"Since when did you become so fond of classification…"
"That, too, is your fault."
And so they headed into the city. Holiday crowds, shops lining the street. Atem walked with his eyes bright.
"That smell… baked goods? The spice combinations of the living world are fascinating."
"Want to try one?"
"No, I'm observing right now."
The seriousness of a researcher. Seto's shoulders shook with laughter.
Then Atem stopped.
"…A card shop?"
In the window: the latest packs, limited edition decks, the Dark Magician—his ace—along with its support cards. Before Seto could say a word, Atem had walked in.
"Ah… card culture has come this far."
"Whatever happened to the romantic act?"
"I know. But this has significant academic value."
"Academic…?"
"Look at this pack layout. The sales strategy is remarkably clever."
Seto watched, exasperated but unwilling to stop him. Atem was examining packs with the same gravity he brought to the dueling field.
"…You're taking this more seriously than the date."
"Both are objects of intellectual excitement."
"The comparison is wrong."
In the end, they spent well over half the time in the card shop. Atem left with a new pack and a full smile.
That evening. The Kaiba mansion.
Over herbal tea, Atem suddenly remembered.
"…Seto, today was a date, wasn't it."
"You finally noticed."
"I'm impressed with myself. I completely forgot partway through."
"Obviously."
After a brief silence, Atem laughed—a little sheepishly.
"Even so, it was fun. I'm satisfied."
"If we define date as time spent sharing happiness together, then it was a success."
"Good. Let's do this format again."
"Another card shop?"
"No—next time we actually play cards."
"That's just our daily routine."
Seto laughed and tilted his cup.
Not efficient. Not according to plan.
But in that inefficiency, there was genuine happiness.
Sunday afternoon.
Seto came through from the study to find Atem staring at a tablet with unusual intensity. On the screen: Stay-at-Home Date Special ♡
"…What are you looking at."
"A phenomenon called the stay-at-home date. Apparently this format exists in the living world too."
"Format?"
"Dates come in varieties. I've learned something—we're not suited to the outdoor type."
"Not suited… I won't argue."
Seto exhaled quietly. Last time: three hours in a card shop. The time before: a philosophical debate in a hotel lounge. The presence of romance had been debatable in both cases.
Atem closed the tablet and stood up with enthusiasm.
"If it's a stay-at-home date, we might actually be suited to it!"
"What's the logic?"
"The ideal environment for intellectual beings is quiet and moderate stimulation. Home satisfies both conditions."
"You just don't want to go outside."
"…I won't deny it."
Seto sighed and looked at the ceiling.
"So what are you planning to do?"
"Work through it step by step. First: cook together."
"…Can you use a knife?"
"I know how to handle a sword."
"That's an alarming preamble."
The two of them in the kitchen.
Atem read the recipe and gripped the knife with care—but every movement carried the gravity of a royal ceremony.
"Seto, is this the ritual of finely chopping an onion?"
"It's not a ritual, it's cooking."
"Are tears part of the trial?"
"No. It's a chemical reaction."
"The culinary arts of the living world run deep…"
Seto stepped behind him and guided his hand quietly.
"Like this—ease the hand down a little."
"Like this?"
"Right. Don't take your fingers off, Your Majesty."
"Please—that title destroys my concentration in the kitchen…"
The sound of something simmering was all that filled the air. They glanced at each other and laughed, small and simultaneous.
What ended up on the table was a soup—misshapen, but warm.
Atem held his spoon with full seriousness.
"Seto, is this what home cooking tastes like?"
"More human than royal palace cuisine, I'd imagine."
"Heh. It's something."
A quiet afternoon. Wind moved through the trees outside. Only their laughter drifted through the room.
"…Was the stay-at-home date a success?"
Atem asked. Seto thought for a moment and nodded.
"The moment you didn't swing the knife around, it became a success."
"Next I want to try a movie-watching date."
"Another thing to add to the research list."
"Not research. Practicing love."
"…You've picked up the phrasing."
A smile Seto couldn't quite suppress found its way to his mouth.
The king was a fast and dedicated learner. Just slightly off-axis.
The living room at night.
The lights were down. On the screen: a classic film Seto had chosen—accessible, uncomplicated. Wine and cheese arranged neatly beside him—practically a nobleman's salon. But right next to it, a melon soda and a defiant pile of popcorn had entirely dismantled the atmosphere.
"Atem. Of all the entertainments in the living world, film is a total art form."
"I know. It encompasses music, theatre, painting—everything."
"…You did your research."
"I learned that couples in the living world have a custom of watching films together."
"A remarkably cultured motivation."
Atem sat up straight and fixed the screen with a serious gaze. Black and white images, a heavy narration. But less than ten minutes in, his brow had already drawn slightly together.
"…Seto, why are these two being so careful with their words?"
"Because restrained emotional expression is considered a virtue."
"Suppressing emotion—is that some kind of crime?"
"No. Aesthetics."
"I can't understand it from the start. Beauty isn't hiding the truth."
Seto laughed despite himself.
"How did it work in your time?"
"I haven't personally experienced it, but probably… if you loved someone, you held them. If you wanted to hold them, you held them. Because that's what I do."
"A difference in civilization."
"Hardly. You hold people too. If anything, this is regression."
The film continued.
The climax: the protagonist leaves his lover behind and goes to war. Atem leaned forward.
"Seto, why does he go? She's crying."
"Duty. To protect the country."
"…And does it actually protect them?"
The screen's light fell across Seto's face as he looked away.
"It does. Someone's decision keeps something going."
"Keeps going…"
Atem murmured it softly. The faintest breath of the afterlife moved through the words. The king he was and the person sitting here now overlapped, lightly.
The film ended. Credits rolled. After a small silence, Atem spoke.
"Seto, why do you think the people of the living world put so much of their hearts into continuing?"
"Because that's what living is."
"…In the afterlife, eternal ending rules everything. But in the living world, it's continuing that rules."
Seto tilted his wine glass and laughed, briefly.
"Because there's an end, you continue. Is that why you've stayed in the living world?"
Atem didn't answer. He just kept watching the screen. The film's lingering warmth was still in the air.
"Seto."
"What."
"Continuing—it's a difficult thing, isn't it."
"But you can do it. You're a king who learns."
"Not as a king. As who I am now—I want to learn. Slowly."
Seto set down his glass and exhaled.
"If you're going to learn, the material is right here."
"Material?"
"Me."
Atem laughed quietly.
"That's expensive material."
"The fee is—your work, and an occasional smile."
"That'll cost you."
"I don't mind."
They sat side by side, watching the credits in silence. The white of the screen moved slowly across the space between them. A time belonging only to the two of them—neither the afterlife nor the living world.
"Are you watching something else?"
"A romantic comedy. I need empirical support for the theory."
"…You're already more than diligent enough."
Their laughter overlapped, quietly. That sound continued, gentle and unhurried, for a long time.
One night. The study of the Kaiba mansion.
The wall-spanning screen showed something like a satellite image of the afterlife. Sandy earth, shimmering light, the royal temple. Seto's afterlife observation system—built by pouring the full force of living-world technology into it.
"…Stable. Even without the king."
Seto murmured it to no one.
"Who are you talking to?"
Atem's voice came from behind. Seto shrugged lightly.
"The thing I'm monitoring."
"Monitoring."
"A figure of speech. Situation observation. Maintenance confirmation. Scientific measurement."
"In other words—checking whether it's all right if I don't go back."
"You catch on quickly."
Atem smiled.
"Seto, I've noticed. You've stopped telling me to go back."
"You wouldn't listen if I did."
"…That's true, actually."
"Meaning I'm simply being rational in my silence."
"Rational silence… the poets of the afterlife would weep."
Seto smiled with just the corner of his mouth and pointed at the light of the afterlife on the screen.
"Look. The priests are maintaining order. It functions without you."
"…But the king's seat sits empty."
"It's symbolic. No practical impact."
"How like you, to file that away as no impact."
"I could project a Solid Vision image instead. Incorporate an AI to make it convincing."
"…No."
A brief silence. Then Atem's voice turned quietly serious.
"Seto. Spending too long between the afterlife and the living world—the soul loses where it belongs. I know that."
"And?"
"…Even so. I want to stay here."
"Then stay."
"Don't make it sound so simple."
"It is simple. If the soul won't stabilize, stabilize it. Build a physical anchor and fix the coordinates to the living world."
Atem laughed, exasperated.
"You want to solve a mythological problem with engineering."
"I'm used to dealing with gods."
"…I'm not a god, you know."
"Setting that aside—in my reality, you're a special case."
The way Seto said it made Atem go quiet without meaning to. Something settled, faint and weighted, like a quiet confession.
"…Seto."
"What."
"Your rationality is sometimes very emotional."
"Your emotion is sometimes very rational."
Their eyes met. The light from the screen reflected in both their eyes—flickering, like the fires of the afterlife.
Atem exhaled softly.
"I might not be able to go back."
"You won't be going back."
"Seto."
"…If that world stops being where you belong—I'll make this one where you belong instead. That's all."
Silence, and a resonance deeper than words, moved quietly through the air between them.
A few days later.
Atem stood at the boundary between the afterlife and the living world. He was about to return to the afterlife—to check on things, to confirm the theory had held.
A thin membrane of trembling air. That was the border.
"Seto, I've been thinking. Have I stopped fitting the definition of the dead?"
"What would make you stop fitting it?"
"Memory, emotion—I've been exchanging both with someone from the living world. What's different from being alive?"
Seto was quiet for a moment, fingers folded in front of his terminal.
"Belonging is determined by will, not physiology. As long as you choose the living world—choose me—the afterlife has no claim on you."
"…That's very you."
Atem's voice was peaceful, and somehow a little sad.
"But if I lose the afterlife entirely, the concept of me disappears. The root of my existence might start to shake."
"Then keep it from shaking."
Seto's voice was calm, but there was something almost amused in it.
"If a world holds together through logic, you can build a bridge with logic."
"You actually intend to build a bridge?"
"Bridge… no, a gate would be more accurate. It needs to be reversible. Closed, but still connected."
"…A gate to travel freely between the afterlife and the living world? You intend to set foot in the domain of the gods?"
"The division of domains was made for human convenience. Logically, the worlds have always been in contact."
Atem shrugged, just a little.
"Your logic is sometimes more frightening than the afterlife."
"I'll take that as a compliment."
A small silence. Then Atem smiled, faintly.
"…It would be funny if the door opened straight into your room."
"That's achievable. Should I implement it?"
"That was a joke, Seto."
"I optimize even jokes."
The afterlife.
The nights there were silent in a way that was somehow alive. Atem sat on the throne with his eyes closed. Behind the stillness, he felt a faint awareness—a gaze.
"…Again, Seto."
At the same time. The research lab in the living world.
Seto raised an eyebrow slightly at the light of his terminal.
"He noticed. I pushed the observation precision too high."
The connection opened. Atem's voice came through, somewhere between amused and satisfied.
I don't particularly mind being monitored. But since when did you develop a hobby of watching over people?
"The afterlife's fluctuation is unstable. Tracking the coordinates of your existence is simple risk management."
Observation with the name of interference. The gods of the world would be angry to hear it.
"Let them be angry. I'll keep gathering data."
Atem laughed softly.
So even their anger is part of the data.
In the back and forth of that exchange, the temperature of each other's voices drew steadily closer.
Then one evening.
Atem reached for the door of his private room. From the other side came, inexplicably, the air of the living world.
Puzzled, he pushed it open gently—and found Seto standing there.
"Finally finished."
"…You tampered with the gate of the gods."
"I didn't tamper with it. I aligned the coordinates."
"…I see. So if I step through this door now—"
"There's an anchor too. Me. Which means you can come through whenever you want. No more falling in like last time."
Atem was quiet for a moment, then laughed.
"…You can choose, by your own will. Though at this point it's less coming and going and more living together."
Seto shrugged.
"What are you saying at this point. Anyway, it doesn't matter either way. The definition of a boundary is just the wording in a contract."
"You think attaching a reason to something makes everything permissible."
"You're the one who allows it."
Between them, the air of the afterlife and the living world melted quietly into each other. The gate stayed open, and neither of them remembered to close it.
Morning. The bedroom of the Kaiba mansion.
When Atem woke, Seto wasn't beside him. In his place, a terminal on the desk glowed faintly.
Afterlife duty today—not in. Back tonight.
A message from Seto. Atem narrowed his eyes and smiled.
"This… might be what they call a dual-income household. Or maybe that's just what it is."
He thought about it over bread in the dining hall. Seto often transferred through the gate on his commute—got there instantly. Atem could too, but on the days Seto was around, he'd get bundled into a car and lectured about wasted commute time, despite there being no traffic or red lights involved.
On his own, though, he somehow felt he had to take in the morning air. So he walked.
The receptionist at the company greeted him with a smile.
"Good morning, Atem-san. Walking today?"
"Walking organizes my thoughts. The transit systems of the human world are actually quite well designed."
Meanwhile, in the afterlife.
Seto was running lines of light through what he'd unilaterally named the Afterlife Technology Bureau.
A priest looked up with a bewildered expression.
"Seto-sama, is that… a soul flow control device?"
"More precisely, a stabilization server."
"S-server…?"
"Setting up a network in the afterlife. The bandwidth isn't sufficient for the king to send directives from the living world."
The priest nodded, half in tears and not understanding a word.
"Will we… be able to follow along…?"
Seto smiled—a rare thing.
"Don't worry. Atem struggled at first too, just with where to save files in Excel."
"…Exseru?"
"…A divine tool."
The priests went pale and began to pray. Another new faith was born in the afterlife.
Evening.
When Atem came home, Seto was already there, waiting. Still in his suit from the afterlife.
Atem hung up his coat and said, "Good work today—to both of us."
"I got them to agree to network optimization in today's meeting."
"Hm. Broadband has finally come to the afterlife."
Seto sipped his coffee and laughed quietly.
"A priest came to me in tears because the line dropped during your remote meeting. So I fixed it."
"…It's getting too convenient. The afterlife is going to stop being the afterlife."
"Then the word afterlife will need to be redefined."
Atem burst out laughing.
"You genuinely intend to update the concept of death."
"Inefficient systems get replaced. That's all."
A conversation that could have been a very intellectual domestic argument. But afterward, the two of them ate the same meal together and laughed.
Late night.
In the corner of the room, the gate glowed quietly.
Atem looked up at its light and murmured.
"Still strange, isn't it. The afterlife and the living world, connected right here."
"Boundaries only ever exist where humans drew the line."
Atem turned. Seto was standing there. In the soft light, his voice took on just a touch of warmth.
"If here is where you want to be, the logic can follow afterward."
"You have more flexibility than any god…"
"Gods created the world. I just rebuild it."
Atem smiled and drew closer.
"The results of the rebuild aren't bad."
Seto's mouth curved slightly.
And then silence settled between them. The light from the gate was warm—like a lamp left on at home.
Morning.
Pale light filtered through from beyond the gate connecting the afterlife and the living world.
Atem brewed coffee and turned the pages of a newspaper—a financial paper from the living world, naturally. Beside him, Seto was reviewing afterlife network data.
"That still looks complicated. What are you analyzing?"
"Soul throughput data. The dawn has been coming earlier in the afterlife lately."
"Earlier dawn… does the afterlife have phenomena like that?"
"It does. It seems that when the king smiles, light moves."
Seto made a show of leaning over to look at the paper.
"Smile for me. I'll verify it with data."
Atem set down his coffee cup in exasperation.
"You're probably the only person who tries to measure a king's smile scientifically."
"If I can't measure it, I'll simply report it as a phenomenon."
"You'd write illumination increase due to king's smile in the report?"
"Factor in world stability: subjective happiness. That's what I'd write."
Atem started to speak, then laughed and shook his head.
"…Your reasoning is sometimes too sweet. It's a problem."
"It's more logical than sugar."
"Don't get flustered using logic."
Seto touched the rim of his glass and said, quietly:
"Being interfered with by the sound of your laughter—it's not bad."
Atem looked down for a moment and steadied his breath.
"Then tonight I'll add more data."
"As an experiment?"
"As personal interest."
A soft silence moved between them. Outside the window, the skies of the afterlife and the living world overlapped. There was no longer a boundary in either direction.
The king of the afterlife and the scientist of the living world. Living in the same house, analyzing each other—bound not by logic or magic, but by understanding.
The scent of coffee. The faint startup sound of a terminal.
Today, again, their daily life began.
