[In front of Yunseul's café, just outside the school gates]
The moment they stepped inside, the air felt like a relief.Cooler than outside—
circulating smoothly thanks to the humming ventilation fans and the faint shimmer of cooling film on the walls.
"Oh, you two came together?"
Yunseul's eyes flicked toward Ji-hyuk, her tone warm with familiarity.
"What can I get you?"
Jian spoke before he could answer.
"He's more of a hot-tea type… but Ji-hyuk, how about we go iced today?"
Ji-hyuk chuckled and nodded.
"Then… two iced yuzu blends, please!"
They walked down the narrow alley that led toward the school, each holding a tumbler in hand.
For a while, they said nothing—just the soft thud of their footsteps against the pavement.
Jian hesitated, then spoke carefully.
"Hey… about that day, when you and Sia were talking about the math lecture… I heard it too."
Ji-hyuk turned his head toward her.
"Oh, that? The online math course? I'm taking the same one as Sia," Ji-hyuk said.
"You okay with it?"
"Yeah. The content's fine, but it does get a bit slow when I'm listening alone."
Jian nodded.
"…Then how about we do it together? Like a study group. At my mom's café, after school.
It's cool and quiet, so we can focus—and if we get stuck, we can help each other out."
Ji-hyuk blinked at the unexpected suggestion, then gave a small smile and nodded.
"Sure. That sounds good."
From a distance, the steady footsteps of students heading to school could be heard.
Beneath them, the asphalt shimmered and sizzled in the heat.
Jian slowed her pace, a faint smile on her lips.
Somehow, the sweltering air that had been pressing on her moments ago felt a little less heavy now.
The school gates weren't far.
She and Ji-hyuk walked side by side—
one hand holding a shared tumbler, the other adjusting her sun-shield glasses.
A little further down, a row of artificial-meat lunch trucks came into view.
Across their sunlit metal exteriors, bold letters were printed.
『High-Protein Alternative Lunchbox – Soy Steak & Insect Protein Bar』
Jian stopped in her tracks and tilted her head back, twisting her lips into a half-smile.
"I don't even remember what sweetness used to taste like anymore."
Ji-hyuk chuckled quietly beside her.
"They say the protein content's gone up since last year."
"That's probably because bugs are cheaper than meat."
"Maybe someday even protein bars will be rarer than real chocolate."
Jian let out a short laugh and shook her head.
"Seriously, the future seems to be arriving in the strangest kind of honest way."
At the far end of the school's outer wall, a small prefab building came into view.
A sign read: Climate Emergency Response Center.
Near the school gate, a teacher in a mask was taking attendance, while a few students sat nearby, wrapped in emergency cooling packs.
Jian glanced in that direction.
"They say at least one or two students get taken there every day. Yesterday, Min-seo from the next class collapsed after P.E."
Ji-hyuk quietly lifted his wrist to check the temperature monitor he was wearing.
On the small screen, a faint message blinked.
『Caution: Rising body temperature. Hydration and cooling break recommended.』
Almost unconsciously, he ran a hand over the back of his neck.
"Even breathing, even surviving… it all feels like living in a disaster movie now," Jian said.
Ji-hyuk gave a silent nod.
A brief, cool silence settled between them.
As they stepped through the school gate, the ground was paved with dust-absorbing tiles, and the landscaping plants on either side curled their leaves in response to the temperature sensors.
Jian tilted her head back to look at the sky.
It was closer to pale yellow than blue, and on the side of the building, a plaque reading Climate Crisis Response – Outstanding School glimmered faintly in the light.
"Our generation doesn't experience the real seasons anymore," Jian murmured.
"Spring is dust storms, summer is heatwaves, droughts, and flash floods.
Autumn is typhoons, winter is wildfires, deep freezes, blizzards, and blackout drills…
The livable springs and autumns just pass us by. Now it's only the occasional nice day wedged in between disasters."
Ji-hyuk gave a heavy nod.
"I just think… we're lucky those nice days still happen sometimes."
Jian turned to look at him.
"That's more optimistic than I expected."
"Well, without those days, there'd be no reason to smile for no reason."
As they stepped into the hallway, the heat-detection tiles on the floor shifted color with every footprint.
Ji-hyuk glanced at Jian and asked cautiously,
"So… starting today, want to do our study sessions at your café after school?"
Jian's eyes lit up, and she nodded.
"Sure. Mom's probably already set aside a grapefruit blend for us."
The classroom door slid open, letting in a wave of warm air and the low hum of morning self-study.
They stepped inside together.
They had no idea what kind of day awaited them, but for now—standing side by side—it somehow felt bearable.
[2028 – Night, Department of Transportation Technology Research Lab]
The research lab was empty, its fluorescent lights flickering with a cold pulse.
Outside the window, the heavy darkness of a summer night had settled in.
Hanna sat with her head resting in one hand, eyes fixed on the monitor.
It had been hours.
On the screen in front of her was the Emergency Smart Circuit Network Implementation Proposal, polished and ready for submission.
Success rate: 67.1% —A decent figure on paper.
But Hanna knew all too well that this alone would not overcome the fear and skepticism gripping the city.
"…This won't convince them."
She murmured the words under her breath.
'If I could predict the public's reaction…'
'Or even find another possibility…'
Hanna slowly picked up an old note from the corner of her desk.
『EchoLink – Beta: Unofficial Future Prediction Simulation
It was just a single line.
A program once rejected for official adoption by the Department of Transportation.
Its accuracy had never been fully verified—a piece of tech abandoned after being used only in limited test runs.
"They told me not to use this."
Hanna let out a short, dry laugh.
But at this point, she had nothing left to lose—and nothing left to protect.
Finally, she exhaled and powered on the dusty computer.
An old system interface slowly flickered to life on the monitor.
『EchoLink – Beta Version – Connection Available』
Hanna hesitated for a moment, then cautiously logged in.
Her fingertips trembled as they tapped across the keyboard.
『Request:Analysis of success probability and public acceptance for Smart Transit Circuit Network implementation.』
Submitting the request, she leaned back in her chair and closed her eyes.
"History will probably record this as a failure… but still, maybe I can borrow another perspective—just once."
It was then that the monitor began to flicker, accompanied by a low hum.
『EchoLink System – Attempting Real-Time Connection to External Respondent…』
Hanna slowly opened her eyes.
Watching the faint connection screen spread across the monitor, she found her fist tightening without even realizing it.
'Please… let someone answer.'
[2050, Second Floor of Yoonseul's Café]
Even after sunset, the August heat refused to loosen its grip.
In the café's second-floor study zone, the air conditioner—restricted by an aging power-limiting system—never cooled past a set temperature.
Only the ceiling's quiet circulator pushed the heavy air in slow, steady loops.
Outside, deep red evening light stretched long across the building's walls, pouring through the windows to pool in hot patches across the tables.
Filtered through the curtains, the glow softened—but the heat dissolved into the air remained sharp and tangible.
The three of them sat in silence, each with a laptop open.
Behind the screens, beads of sweat traced a slow path down their necks, and on the desk, lukewarm herbal tea—rather than cold water—was their only small comfort.
Jihyuk occasionally tugged at his shirt collar and rubbed the back of his neck,while Shia tapped her tablet pen lightly against the beads of sweat forming on her forehead before stopping.
Even in the oppressive heat, Jian sat by the window, eyes fixed on her laptop screen.
Small droplets of sweat dotted her face, yet her gaze stayed steady.
Jihyuk turned his laptop slightly toward her.
"This is the math lecture site I usually use," he said.
"The instructors explain things well, and if you ask a question, the AI will answer."
Jian studied the screen for a moment before nodding.
"The UI's more intuitive than I expected. The search function works well, too."
Shia let out a quiet laugh and added her own comment.
"Jihyuk even finds the lectures here and makes summary notes?
We were talking the other day and I was honestly surprised," Shia said.
Jihyuk gave a sheepish smile.
"I haven't been at this school for long, so… not many friends yet. That leaves me with a lot of free time."
They continued chatting as they browsed for the next lecture—
When suddenly, a completely different kind of notification popped up at the bottom right corner of Jian's laptop screen.
『Connection Request Detected – AI Simulator (LUKA) / Session Code 2028-HN01』
Jian's eyes widened in surprise, and she quickly closed the pop-up as if covering the screen.
Jihyuk seemed to have caught a glimpse of it but said nothing, quietly winding up his earphones instead.
A few minutes later—
『Reconnect Request – LUKA / Currently Waiting for Connection』
The pop-up appeared again.
This time, Jihyuk's eyes stayed fixed on her laptop screen.
"…Jian. What is that? That's the same thing that just popped up, right?"
Jian tried to sound casual as she moved to close her laptop, but hesitated halfway.
"Oh, that? It's just an old AI simulator I used to test ages ago. I turned off the auto-alerts, but… no idea why it keeps showing up."
Her words were nonchalant, but her eyes betrayed unease.
Shia, too, avoided their gaze.
And then—
A third pop-up appeared.
『LUKA – Causality-Based Session Request Received / Confirmation Required』
Jihyuk pointed at the laptop and spoke carefully.
"This… there's no way that's a normal alert from an online lecture site. You're hiding something, aren't you?"
Jian and Shia exchanged a glance.
A brief silence.
Then Jian slowly turned her laptop toward Jihyuk.
Her expression held a mix of resolve and caution.
"…This might be… really hard to believe. I haven't told anyone else before,but I think I can tell you," Jian said quietly.
Shia spoke next, her voice just as calm.
"This is an AI simulator called LUKA.
Through it… we've been connected to someone living in the past."
Jihyuk's brow furrowed slightly.
"The past? Like… a time machine?"
"Not exactly," Jian replied. "It's a system that lets us talk to people in the past."
She went on, slowly and deliberately.
"We've already done it once together—and before that, I did it alone.
We've made small changes in the lives of the people we connected with… and those changes have left traces in our world today.
No one remembers them except for us."
Jihyuk looked back at the screen.
A name and a date he didn't recognize were glowing in the alert window.
『Requester: Lee Hanna / 2028.08.10 / Request for Transport Design Review』
"…So this is… really from someone in the past?"
Jian nodded.
"Yeah. And it doesn't look easy this time. Last time, it was about a contest project and whether to install solar panels.
But this… what we say now could end up changing the future of the city's entire transport system."
Jihyuk drew in a short breath and glanced around the room.
On the café's second floor, the world outside remained calm, but what was unfolding here was a quiet turning point.
"Then…" Jihyuk began.
"You're saying… what we say now could actually change someone's future?"
Jian nodded firmly.
And in the center of the screen— a new message appeared in silence.