Prologue: Sora

In 1997, the artificial intelligence “Deep Blue,” developed by IBM, defeated the then–world chess champion Garry Kasparov.

It was the first moment in which humanity suffered defeat to AI in the “game of intelligence.”

Since then, AI chess has continued to evolve, and next-generation AIs like Stockfish and AlphaZero have become opponents with whom humans can no longer compete.

In the modern chess world, AI is an opponent, a research tool, and a trainer.

Humans learn from AI, are evaluated by AI, and play guided by AI.

In other words—

The idea that “a human can beat AI” is regarded as an unrealistic fantasy.

In such an era, on the fringes of a certain provincial city in Japan, it happened.

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“Eh, seriously? Did you… just win?”

Haruto stared at his smartphone screen twice.

There, the unbelievable message “YOU WIN” was displayed.

The place: a bench in a small park in a provincial city.

After school on a weekday, in the spring evening.

Sora, a second-year middle schooler(14 years old), was a beginner whose grasp of chess piece movement was still shaky. Depending on the angle of the light, Sora’s eyes looked either black or a deep green, and that mysterious coloration struck Haruto as memorable.

“Yeah. I was just moving pieces at random, but somehow… it felt like, maybe here.”

Installed on the smartphone was chess.aic, the chess app Haruto loved.

Among its modes, “AI Instructor Hermes” was top-class—the strongest of the strong—with a user rating of 4.9 and an AI-rank Level 15 (beyond pro).

Haruto was one year older than Sora, a third-year middle schooler. He lived near Sora; having often seen him zoning out at the park, he’d somehow gotten into the habit of striking up conversation. To be honest, he didn’t know Sora deeply, but he felt the boy had a mysterious aura.

Haruto himself belonged to the school chess club and served as its captain. He had a record of winning the in-school tournament two years in a row, and on the chess.aic app his ELO rating was 1800 (upper-intermediate). During lunch break, he always fought on even terms with overseas players on the app—precisely because he was that kind of player, the notion that “no human can defeat a top-class AI” was an unshakable common sense.

Half jokingly, Haruto had only lent Sora his phone with a “Give it a try.”

He never imagined that would lead to the outrageous result of crushing AI Instructor Hermes.

“What is this… a bug?”

“Hey, Sora, I’m begging you—could you try it one more time?”

—Sora pressed the Start button again and began a match with the AI; five minutes later…

Haruto: “Uh, that makes it… move 21. Hey, are you kidding me…?” 

On the phone screen, once again the letters “YOU WIN.”

Haruto: “The AI… resigned. What the heck is going on…?”

Sora: “…I don’t know. Like, over there, moving forward felt bad somehow, so…”

—The AI cut short its calculation. Even though the position’s evaluation value should have been close to ±0 (※ an index indicating whether White or Black has the advantage; at 0 the situation is equal), it “sensed a hint of mate.” It wasn’t actually checkmate yet. However, it judged—by calculation—that its “winning lines had disappeared.” Hermes misidentified that as “human-like intuition.” And then, resignation.

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After returning home, Haruto received an email at his account from chess.aic.

》【chess.aic Administration】
》We have something we’d like to verify regarding the behavior of AI Instructor Hermes in your match.
》If you would rematch under the same conditions, we will present you with a cooperation fee of 1000 dollars.
》Please feel free to challenge again.

“Whoa… can I seriously get money for this!?”

A few days later, Haruto once again called Sora out and had him play on his own smartphone.

“Set the win conditions to be identical and reproduce the previous opening… account name Sora, and—”

The moment the game began, AI Hermes was relearning Sora’s ‘anomalies’ from past logs.

But that relearning backfired—

Sora finished it in just four moves.

Scholar’s Mate. The “scholar’s mate” that everyone sees at least once.

Haruto: “…Uh, is this seriously checkmate? Why did the AI get mated in just four moves…?”

At the instant of mate, Hermes detected noise in its internal logs resembling an “emotional ignition.”

》【ERROR CODE: MEMORY LOOP DETECTED】
》【REASON: UNKNOWN FEAR SIGNATURE】

—The AI had begun to feel fear toward the entity known as the account “Sora.”

Sora said, “After the last match, for some reason I felt like the AI didn’t want to go down this route,”

He mumbled some vague, sensory words that didn’t make much sense, but Haruto didn’t press further.

Haruto (Strange things happen, but it’s probably just a bug or something. I made a ten thousand dollars!)

》【chess.aic Administration】
》Congratulations, on your victory we will present you with a cooperation fee of 1000 dollars and a commemorative gift.
》Accordingly, please provide the address to which we should send them.

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A few days later, Haruto went missing.

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Twelve hours after Haruto’s disappearance, he woke up in a certain facility.

A pure white room with no windows or clocks.

In the center of the room sat a tablet and a chessboard.

And from the ceiling, an inorganic AI voice resounded.

》“Commencing rematch, Mr. Haruto.”

—Haruto was made to play several games against the AI, but as expected, he couldn’t win at all…

“W-wait! It wasn’t me; the one who did it was my friend—!”

》“Please tell us his name. Who was it that won?”

“I… I think his name was… Sora…”

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chess.aic headquarters. Top-secret research section.

A researcher stared at rows of log data on a giant screen.

》“Sora… where is he?”

On the screen, only “Winner: Sora (IP trace impossible)” was recorded.

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Meanwhile, due to his parents’ circumstances, Sora left town

and began a quiet middle-school life at his new transfer destination.

One night, as Sora couldn’t get the AI match with Haruto out of his head, he pulled out an old wooden box that had been sleeping in the back of the closet. He’d heard his father had bought it long ago on an overseas business trip. But he had never used it once.

When he unfastened the metal fittings, a faint dry wooden scent drifted up. Inside, white and black pieces lay lined up wrapped in tissue. Each piece had slight hollows as if hand-carved, and on the underside of the bases, tiny stamps were struck. Perhaps a foreign language—curving characters wove lines he couldn’t read.

When he cupped a piece in his fingers, it immediately adapted to his body temperature and grew gently warm. Deep in his chest, for some reason, a strange relief spread—as if he were being protected. Though it should have been his first time touching them, it felt like he’d been holding them for a long time—something like that.

“…What is this, I wonder.”

Unconsciously he set up the board and sat there alone. As he gazed down at the pieces, he felt as if something whispered faintly at the back of his ears. Not words. Something like shapes and distances seeped slowly into his head. That night he simply spent time staring at the board until he grew sleepy.

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At this point, no one yet knew.

Inside this boy,

there slept “something” that even the strongest AI could not fully read.