An hour later, Aina is laughing hard enough to forget her lingering fatigue.
It isn’t the fragile sound she made beneath the convenience store lights or the careful smile she gave her mother to keep her from worrying.
She sits propped against the living room sofa, clutching her droopy-eared rabbit plush to her stomach as laughter shakes her shoulders.
Sayuri stands beside the couch, unimpressed.
“It was an administrative error,” she repeats, folding her arms over her school blazer.
“Your mysterious roommate was Saki-kun?” Aina gasps, wiping a tear from the corner of one cherry-pink eye.
“And you both have S.S.
stamped on everything you own?
Sayuri, that is incredible.”
“For less than forty-eight hours,” Sayuri corrects.
“Our matching initials are an irrelevant and highly inconvenient coincidence.”
“It is the most important detail of the entire story.” Aina’s voice rises with renewed amusement.
“I can’t believe you had a territorial standoff over a wooden spice box.”
Color has returned to Aina’s face, leaving her cheeks warm and pink.
Seeing it makes Sayuri’s embarrassment worthwhile.
On the coffee table, Ryosuke’s porridge container sits empty beside two clean melon rinds.
Aina’s attention shifts to the end table.
A chilled bottle of unsweetened green tea rests beside Sayuri’s neatly organized notebook.
A knowing smile touches her lips.
“He remembered,” she murmurs as her laughter settles.
Sayuri adjusts her collar.
“I informed the captain that you had eaten half your breakfast.”
“I wasn’t talking about the porridge.
I meant your tea.”
Sayuri looks at the condensation on the bottle.
“He likely selected the wrong brand.”
“Ryosuke drinks black coffee,” Aina says.
“He knows exactly what tea tastes like.”
“People are capable of purchasing items outside their personal routine.”
“They certainly are.”
Aina says nothing more, but her smile remains.
She sets the rabbit aside and reaches for the last slice of melon.
Before picking it up, she pauses.
Her amusement fades.
“In all seriousness…” Her voice softens.
“I’m really glad.”
Sayuri tilts her head.
“Glad that the administrative office corrected the error?”
“Glad that you were safe.” A trace of last night’s vulnerability returns to Aina’s face.
“I know Saki-kun is a good person—even if he’s as serious as you are—but when you said someone was staying in your suite, my heart sank.
I didn’t like knowing you were sleeping under the same roof as a boy you didn’t know, especially while I was stuck here.”
She adjusts the blanket over her knees.
“I know you can take care of yourself.
You’re an archer.
You notice things before anyone else does.” Her eyes lower.
“But I still worried.
Knowing he’s officially out is a huge relief.”
Sayuri’s posture eases.
She sits beside Aina, close enough for their shoulders to touch.
“How long are you staying?” Aina asks, double checking on the answer, and leaving the melon on its dish.
“Tonight.”
“You have a completely secure and empty suite now.”
“I am aware.”
“And there is no unexpected boy cooking in your kitchen.”
“Aina.”
Another laugh slips from her, light and free of last night’s shadows.
She leans her head against Sayuri’s shoulder.
Sayuri lets her.
She rests her cheek against Aina’s hair and looks toward the bottle of green tea.
The administrative error has been corrected.
The strange family connections can wait.
For now, the living room is warm, safe, and theirs.
The front door chime breaks the silence.
A cheerful greeting carries through the ground floor.
Sayuri’s mother steps inside, her familiar voice filling the house.
Sayuri rises to greet her and returns with a small overnight duffel bag.
Inside are fresh clothes, extra toiletries, and everything else she might need for the night.
Their mothers follow her into the living room, bringing the scent of fresh tea and sweet pastries with them.
“Honestly, you two haven’t changed since kindergarten,” Sayuri’s mother says, placing a bakery bag on the coffee table.
She gives her daughter a fond look.
“You still run off without preparing the moment the other one gets sick.
I had to pack your overnight bag for you.”
“It was unnecessary for you to come,” Sayuri says, though she accepts the bag with a quiet nod.
“I already went to the dorm and collected what I needed.”
“Nonsense.” Her mother waves the objection aside before turning to Aina.
“The clothes were only an excuse.
I needed to see for myself that Aina was alright.”
“And leave Aina unsupervised?” Aina’s mother teases Sayuri from the kitchen doorway.
“We all know that was never going to happen.”
Aina hugs her rabbit tighter.
“Mama knows you too well.”
Sayuri offers no defense.
She lowers the duffel to the floor and checks its contents.
Since returning, she has noticed Aina keeping her tablet close.
Sometimes it rests against her knees.
Other times, she tucks it beneath the blanket beside her.
Even while laughing, she never lets it move beyond reach.
Whenever the screen dims, she taps it awake.
Sayuri catches brief glimpses of narrow columns, dates, and a map she cannot read from across the room.
Once she confirms that her mother packed everything, Sayuri closes the bag and places it beside the sofa.
Instead of joining their mothers for tea, she returns to Aina.
“I have been meaning to ask.” She glances at the tablet.
“What have you been doing on that since I returned?”
Aina’s fingers stop against the edge of the screen.
For a moment, she looks caught.
Then her expression brightens.
“I’ve been organizing what we know.” She moves the rabbit aside and pats the open cushion.
“Come look.”
Sayuri sits beside her.
Aina unlocks the tablet.
A structured grid fills the screen.
Dates sit beside locations, railway lines, weather records, and memory fragments.
A route map occupies the panel beside it, covered in precise annotations.
Sayuri studies the columns without touching the screen.
She recognizes the format immediately.
“You made a ledger.”
“A preliminary one,” Aina corrects, unable to hide the pride in her voice.
“I began it in my notebook, but arranging this much detail by hand took too long.
Every new date or location forced me to rewrite part of it.”
She taps one of the columns.
“I can type quickly, move entries without losing anything, and keep the maps and historical records beside the fragments.”
“So you have abandoned the notebook.”
“No.
I’ll still write in it occasionally, especially when something feels important enough to preserve separately.
The tablet is simply more efficient for organizing the ledger.”
Aina points to the map.
“The snow around Kamishiro is historically consistent.
The station was part of the Oito South Line in 1956, before the full route opened the following year.
Trains were already passing through that section of the Japanese Alps.”
“Then what is wrong?”
“I cannot find the accident.” Aina returns to a page of empty search results.
“The route exists.
The weather fits.
But the derailment does not appear in any record I checked.”
“The records could be incomplete.”
“Exactly.
That is why I am not choosing an answer yet.”
Sayuri examines the evidence table.
“You found all of this after breakfast.”
“I want evidence before Ryosuke turns sixteen lives into a universal rule.”
“You intend to argue with the only person who remembers them?”
“I intend to make him cite his sources.”
One corner of Sayuri’s mouth lifts.
“Now that’s the Aina I know.”
She returns her attention to the ledger.
A gray row sits beneath the four named groups.
Unidentified Participant — Confidence: Insufficient
Two observations appear beneath it.
Setsu/Kagura Fragment — Estimated Mid-Seventeenth Century: Side gate opened before Setsu reached it.
Person responsible absent from memory.
Mayumi/KyokoFragment — Estimated 1950s: Fifth piece of luggage carried for four identified travelers.
Owner unconfirmed.
Sayuri reads both entries twice.
“You believe someone else was there.”
“I believe the memories contain evidence none of the four identified people can account for.” Aina taps the first entry.
“Someone may have opened the gate before Setsu entered the street.
It could also have been left open by a resident escaping the fire.”
“And the bag?”
“The tag may have fallen off.
It may have belonged to one of us.” Aina’s fingertip moves between the two entries.
“Neither observation proves another person.”
“Then why call the category an unidentified participant?”
“Because assigning the evidence to one of the four without support would be inaccurate.” Aina lowers her hand.
“So would deleting it because it does not fit.”
Sayuri looks again at the gray row.
Four names occupy the confirmed columns above it.
Beneath them waits a place without a name.
Another tab remains visible along the bottom of the spreadsheet.
Unlike the plain white tabs beside it, this one is dark blue.
A small lock icon sits beside its name.
Acceleration Theory
Sayuri points to it.
“What is that?”
Aina’s hand moves to the edge of the tablet.
“An unfinished section.”
“Why is it encrypted?”
“Because it is unfinished.”
“That does not answer the question.”
“It contains theories I cannot support yet.” Aina draws the tablet slightly closer.
“I don’t want anyone reading them and mistaking speculation for evidence.”
The answer is logical.
It is also incomplete.
Sayuri studies the way Aina keeps her cardigan closed across her body and the care with which she moves the cursor away from the protected tab.
“What kind of theories?”
“The kind I should finish before showing you.”
“Aina.”
“I’ll show you when they are ready.”
Sayuri considers pressing further.
Aina rarely protects unfinished work from her.
If anything, she usually places early conclusions directly in Sayuri’s hands and demands that she find the weaknesses.
Whatever occupies the locked sheet is different.
For now, Sayuri allows Aina to return to the visible ledger.
“Are you still aiming for the top national university?”
“Of course.”
“Good.” Sayuri moves closer and lowers the tablet away from Aina’s face.
“Then you may resume solving the impossible memory problem after lunch.
Your mother will blame me if you collapse over a spreadsheet.”
Aina saves the visible file beneath a deliberately unremarkable name:
Comparative Architecture Notes
Already, it contains four identified groups of remembered names, one unresolved gray category, four estimated periods, a map of the Oito Line, photographs of the snow route through Kamishiro, the missing derailment records, and four provisional intervals:
Approximately 70-130 years
Approximately 160-220 years
Approximately 270-310 years
Approximately 5–25 years
The protected theory remains separate.
At the top of the visible notes, Aina writes one sentence:
The obvious answer is not automatically the correct one.
For the first time, the memories appear to give her something other than fear.
The columns, confidence ratings, and unanswered questions have turned them into a problem she can approach one piece at a time.
Sayuri takes the tablet from her and places it on the coffee table.
“Lunch,” she repeats.
Aina settles back against the sofa.
“After lunch.”
“That was not permission to negotiate the duration.”
“Fine.”
✦ ✦ ✦
Aina’s mother carries the empty teacups into the kitchen.
Sayuri’s mother follows with the ceramic kettle, and the living-room conversation fades when she draws the kitchen door partway closed.
The warmth leaves Sayuri’s mother’s expression.
She pauses beside the sink and looks through the window.
Unnatural gray clouds gather along the horizon, darker than the rest of the overcast sky.
“It felt cold last night,” she says.
“Not like ordinary winter rain.”
Aina’s mother pours fresh tea into both cups.
“I felt it too.”
Her attention shifts toward the narrow opening beside the kitchen door.
Aina’s voice carries from the living room, lighter than it sounded the day before.
“Something in the air has changed,” Aina’s mother continues.
“The fatigue came so suddenly.
It felt like that time again.”
Sayuri’s mother turns from the window.
“Do you think it has begun?”
“I don’t know.”
Aina’s mother closes both hands around her cup, allowing its warmth to settle into her palms.
“But if the atmosphere is changing this quickly, we cannot wait until we are certain.
We need to prepare.”
“How soon?”
“Soon.”
The word remains between them.
They have shared this understanding since before either of their daughters was born: some dangers do not announce themselves clearly, and waiting for proof can become its own kind of mistake.
Beyond the partially closed door, Aina rests her head against Sayuri’s shoulder.
Sayuri adjusts the blanket over her knees, unaware of the conversation taking place a few steps away.
For another moment, the living room remains warm.
Neither girl knows what their mothers have already begun to fear.
✦ ✦ ✦
Late that evening, the dorm supervisor reviews the transfer student’s electronic record one final time before logging off.
The administration lobby is dark and empty.
Rain taps against the tall glass windows despite the forecast promising clear skies throughout the weekend.
The enrollment database displays Saki’s master profile:
Name: Shimizu Saki
Birthdate: January 1
Year: Second Year — Class 2-B
Emergency Contact: Verified
Sex: Male
Every field is correct.
She opens the secondary housing log.
Housing Category: Female
Residence: Girls’ Dormitory — Suite 307
The supervisor leans closer to the screen.
The error did not originate in Saki’s enrollment profile.
Somehow, the housing system assigned him to the girls’ dormitory despite drawing information from a master record that clearly identified him as male.
She opens the edit history to collect the information for her report to technical support.
Only one revision appears.
Time: 3:17 a.m.
Action: Automated Housing Reassignment
Authorized User ID: —
The change was made before Saki arrived at Tokui.
There is no account attached to it.
No staff identification, system administrator, or automated process code.
The field is not labeled unavailable.
It is simply blank.
The screen flickers.
For an instant, the text stretches into distorted vertical lines.
The fluorescent lights overhead dim at the same time, filling the lobby with a low electrical hum.
Then everything returns to normal.
The supervisor adjusts her glasses and studies the terminal.
The housing log remains open, unchanged.
“I need to have this computer replaced,” she murmurs.
She captures the record for her report, closes the application, and switches off the desk lamp.
Outside, the rain stops.
Not gradually.
One moment it touches every window.
The next, the night is silent.