"How many hours have you been glued to that screen, Mio?"
Night had fallen, and Aya Shinkai had stopped her design work to look over at her. She was tugging at the sleeves of her men's sweatshirt, a worried look on her face.
"Don't touch me. I'm thinking."
"Pushing yourself that hard, you're going to shrivel up." Aya pressed a hand to her forehead in exasperation. "Boss, if you leave Mio alone, she's going to collapse."
Mikoshiba didn't answer that, but quietly set two cans of coffee on the corner of Mio's desk. One was the usual black. The other was the sugary sweet kind Mio liked.
Then, casually, he started talking about the site visit earlier that day. Lightly, as though talking to himself, so as not to break Mio's concentration.
"I went and talked to that veteran worker again today. Though—honestly, I didn't hear anything much."
Mio didn't answer. It was impossible to tell whether she was even listening.
"Just a little more detail about Tadokoro's morning habit, that's all. Apparently he wasn't just looking at the sky—he was comparing it with the day before," Mikoshiba said, and took a sip of coffee. "'It's gotten a good deal colder than last night. Better make extra of the scooped'—that's how he measured the difference from yesterday, with his skin. Not whether that day was cold or hot. How far it had swung from the day before. ...Well, it's just small talk, nothing to do with the problem at hand."
—In that instant.
Mio's fingers, halfway to the coffee, stopped in midair.
Comparing it with the day before. Somewhere in that one remark Mikoshiba had carried in, a small spark flew deep in Mio's head.
What came back to her were the words she herself had said to Mikoshiba, that day in the office. Strong AIs for Othello and Go learn from an enormous number of past games—"the board position, and whether it was won or lost"—and read ahead from the current position. What matters there isn't the number of discs on the board. It's the features of the position, and the difference in the balance of the game, which you can't see just by counting.
She had been looking at quantities the whole time. Maybe that was why she had slipped.
There was no proof yet, none at all. But points she had stored away in separate boxes began, one, then another, to be drawn by feel toward a single word. What image they would form, even Mio herself couldn't see yet. There was only the sense that her fingertips had suddenly brushed the outline of the thing she had been unable to grasp.
The sounds of the world receded, all at once.
The warmth drained from Mio's eyes. All that remained was a light, terribly quiet and terribly sharp. The desk, the cans of coffee, the voices of the two beside her—none of it was in her field of vision anymore. Mio's eyes alone had begun to follow a chain of countless points that no one else could see.
"...It connects."
Mio murmured it almost on a breath. Then she let go of the coffee, spun her chair around, and turned back to her laptop.
"Mio?"
Aya drew back half a step in spite of herself. The same woman who had brusquely said "Don't touch me" only a moment ago looked like a different person entirely. A profile that seemed possessed—and yet a little frightening, and a little beautiful. She had no grasp at all of what had just happened.
"...Himuro?"
This time it was Mikoshiba who called her. But Mio didn't answer.
Hunched over in her chair, her fingers had already begun striking the keyboard at high speed.
Neither Mikoshiba nor Aya could speak to her anymore. To an onlooker, it was just one woman pounding furiously at a keyboard. That was all.
But inside Mio, it was different. Past data piled up over years—and far back in that accumulation, something distant, beyond anyone else's sight, would suddenly come into focus. From the far end of a vast store of records, she would see straight through to a tomorrow that hadn't come yet, or to a reason that had been hidden all along. Mio had always had moments like that. Seeing far, and wide, in a single breath. An instant that could only be called clairvoyance.
Mio was no longer in this side of the world.
To seize, with her own hands, the thing she had caught sight of far, far away—she had long since broken into a run.
That night, the world vanished from the office in Gotanda.
Now she would pass the scattered points onto a single thread. Not to anyone in particular, words spilled from her mouth only in fragments.
"...Not this. Some other way to lay it out..."
Little by little she changed how the numbers were arranged, tried them against it, checked. Tried them, erased them.
"As long as I'm looking at absolute values, it'll slip no matter what... What matters isn't the quantity. Probably, something more—"
"Mio, you really haven't had anything to eat or drink, have you?"
Aya, who at some point had stopped working, called to her from across the desk. Mio didn't turn around. It was impossible to tell whether she even heard.
Mikoshiba stopped Aya with a look. On the corner of Mio's desk, he set down a single can of sweet coffee, without a sound. Mio's fingers didn't stop.
She stopped laying out the line graph as it was, and remade it into the size of the swing from the previous value. On the screen, two waves suddenly fell into step.
"...That's working."
But Mio didn't stop there. She tried fitting the model she'd built to something else. The waveform didn't so much as twitch.
"...This one alone is different. If I try to swallow them all together, it slips. Cut it."
Time melted away.
Writing and erasing, erasing and writing. The sweet canned coffee had gone cold without being touched once.
Outside the window, indigo was turning to a whitish gray. The sound of the first train rang out in the distance.
On the last of the verification checks, green lights came on, one by one.
"...All green."
Mio let her body slump against the back of the chair. The all-nighter had dried her out to the core. Even so, her eyes alone were still shining.
The weapon was ready. All that was left was to unveil it on site.
Mio got up sluggishly and grabbed her jacket.
"...Let's go, Mikoshiba."
Mikoshiba, who had stayed up all night on the sofa, gave a little smile and picked up the car keys.