Chapter 11:
Caïssa’s Child: The Boy Who Beat the AI
Iori (White)
The embodiment of a 2100 ELO textbook proceeds in textbook order. Slowly the center, slowly develop, a no-excess-no-deficiency handling. The moment the opponent overextends by one move, a central thrust fixes the shape, and a quiet pressure rises from behind. At the doorway to the endgame he lightly trades rooks; with the pieces reduced, his edge takes clear form. What remains is a “winning shape” straight out of the manuals.
“This is just like practice from here,” he murmurs under his breath, and finishes with a diagram straight from the textbook.
Even the opponent’s sigh upon resignation somehow sounds polite.
Momoko (White)
From the first move she marks a light tempo. Knight leap → bishop’s glare → a tiny sac to open a line. Her opponent’s shoulders rise slightly. Momoko’s gaze runs diagonally, she shows only the shadow of a double attack, then stabs along a different line.
In under five minutes, the area around Black’s king lines up into a “nice fragrance,” and she places a slender move.
On move 21, the opponent double-checks the clock and resigns. “...Thank you very much.”
Momoko winks. “Hehe, you like tactical perfume, don’t you?”
Sora (Black)
Three minutes in. The venue HVAC is a low bass, the opponent’s breathing grows shallow on the second beat. Sora doesn’t look at the clock. Inside his fingers he counts 1, 2, 1, 2, 3 once, and places a single “wait.” The board gradually jams up, and White’s own pieces build a self-made wall behind the white king.
—And then, from outside conscious awareness, the black knight’s blade pierces the white king’s throat.
The escape squares are packed with White’s pieces.
》 Spectator: “A beautiful smothered mate.” Quiet applause. Finish time 10:10.
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【Round 2 (Boden’s Mate)】Momoko (Black)
Two or three probing moves in the opening. Seeing tiny bubbles of fear rise in the opponent’s gaze, Momoko quickens the pulse by a half step.
Fear Spike.
That cold discomfort where you can see the candidate move but can’t bring yourself to touch it spreads over the board.
White stares at the “untouchable move.” At the edge of their vision, another black line quietly opens its mouth.
On move 21, the clock stops at 0:13. “...I resign.” Momoko shrugs and smiles, “It’s not scary—if you look properly.”
Iori (Black)
From the opening he’s calculating the outline of the endgame visible beyond the mass exchanges.
“This is a long battle of bishop vs knight,” in a voice only he can hear.
He offsets the pawn structure by one rank and keeps the opponent’s king far away. With a triangle maneuver (triangulation) he yields a tempo and squeezes to a point close to zugzwang. (※Zugzwang: a situation where having to move worsens your position, so you’d rather not move if you could.)
Not “you can resign here,” but after constructing the diagram, he gently offers his hand. The opponent obediently toppled the king on its side.
Sora (White)
The taut air over the board suddenly wavers. The instant the opponent carelessly moves a knight, Sora’s breathing and the venue’s pulse line up exactly.
The queenside bishop slides diagonally in, driving the black king toward its escape route. Immediately the kingside bishop cuts sharply from afar. Two beams cross, and the black king is immobilized, surrounded by friendly pieces.
》 “...Two bishops crisscrossing to mate—it’s Boden’s Mate.”
Someone in the spectators mutters, and silence spreads.
At the same time the second hand points to 10:10, a referee raises a hand. “Checkmate.”
The X etched on the board proclaimed a certain victory behind Sora’s impassive face.
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【Round 3 (21 moves and 10 minutes 10 seconds)】Outside the spectator rope, a boy holding a paper cup of water whispers, “That girl did 21 moves again.”
Another kid looks at his notes and is startled. “R1 and R2 were 21 moves too. Are they seriously standardizing on 21?”
Momoko looks over the final position and laughs from her shoulders, “Haha, 21 moves again, I’m dying♡” Her winning lines close perfectly every time, like fragrant short stories.
Beside her, another murmuring.
》 “Hey, that black-haired kid… isn’t he freakishly fast? Only his opponents are using time…”
》 “You’re right…”
Sora doesn’t hear it. No—he’s simply dissolved into the venue’s pulse.
1, 2, 1, 2, 3. Move. The position collapses without a sound, and when the opponent notices, they’ve blocked the escape route with their own pieces. And when the opponent’s king is laid on its side, the clock is once again 10:10.
》 “No way! Look—every time the black-haired kid finishes, the clock stops at 10:10. R1, R2, and now R3.”
》 “R1, R2, R3… all 10:10? Lemme screenshot—ah, I turned in my phone.”
》 “What are these people… monsters?”
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【Round 4 (Time melting away)】The opponent is a previous tournament top finisher. He has a habit of holding his breath when he moves.
Before the start Sora makes the first two beats of a 5/8 meter, a breathing so quiet it could reach the tip of the opponent’s nose.
In the middlegame, the white king is still safe; evaluations are equal.
Sora prepares an equal two-choice.
Qh5+ and Qg4+. The evaluation doesn’t change depending on the choice. Either is fine. Precisely because of that, it eats time.
The opponent holds his breath. He cannot move by beats three and four. On beat five, hesitation seeps in.
Sora shows A then plays B; next he shows B then plays A. He keeps offsetting the pulse of choice.
There’s no visible UI (screen) to display evals here, and yet the sound of candidate moves being trimmed away mingles with the venue HVAC.
“...This is weird, the game won’t progress,” someone in the spectators mutters. There’s no screen showing an evaluation bar in the hall, but while the scent of equality remains, only White’s time melts away.
Anxiety lights in the opponent’s eyes. He holds his breath; his fingers lock up. Sora, at a 1:29 rhythm, offers another two-choice.
At last White reaches for the second-best and stops mid-move.
“...I resign.”
A quiet resignation. The venue buzzes, and everyone who looks at the clock sees it stopped at 10:10, and they look at one another.
Sora gives a light bow and does not look at the clock. Instead he confirms that the venue’s pulse is still overlapping his chest.
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【DQS (Direct Qualify, and the mystery of 10:10)】Players’ lounge. Paper cups of water and a dish of salt tablets.
On the bulletin board, a quick-post sheet. Under “DQS Achieved (4.0/4),” the names Iori / Momoko / Sora line up. A murmur of “too fast” spreads through the hall.
“Okay—what about Round 5?” Iori pulls out a chair.
“I’ll play,” Sora answers immediately.
Momoko pokes his shoulder. “Nie (no), don’t. We’re in nationals—that’s plenty. Let’s call it a day.”
Sora hesitates a moment, then nods. “...Got it.”
Iori smiles. “I’ll switch to helping the staff here too. So the three of us will withdraw from R5 and lock in 4.0. Saving stamina before nationals is also a kind of strength.”
They stand at the same time and submit withdrawals at the desk. The referee is surprised, then quickly shows understanding. “Congratulations on DQS.”
Momoko runs up to Sora.
“Congrats on nationals! Look, look—I lined all mine up at 21 moves. Isn’t that awesome?♡”
“Mm… Ah, mine all landed at 10 minutes 10 seconds.”
“...Huh? All of them!? You’re right… Why!?”
“I was playing on 1 minute 29 seconds, so it turned out that way.”
“Co jest, kurwa!? (What the fuck!?)”
“With 5/8 time, if you line 1 minute 29 seconds = 89 seconds up on beat one, it naturally gives 610 seconds = 10 minutes 10 seconds.”
“...What is that math-y talk—terrifying!”
Momoko was bad at math.
“The Fibonacci sequence. The thing where you add the previous two numbers to make the next. 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610…”
“Wait—my 21 moves are Fibonacci too!”
“Right. The rhythm of nature is made of that everywhere. Petal counts, spirals, shells, sunspots… Nature is mysterious…”
“No, you are more mysterious than nature!”
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【List of Nationals Qualifiers】Evening.
A crowd in front of the bulletin board. The blue header “Nationals Qualifiers (DQS & Top Tiebreaks).”
On the printed sheet, the names Iori / Momoko / Sora line up straight.
Sōma: “Whoa, never mind Iori-buchō and Momoko, even Sora’s going to nationals!”
Akira: “Sora’s only been playing chess for a month… Right? Was he actually a beginner!?”
Momoko casually links arms with Sora.
“Mm-hmm♡ I told you—when Sora does it, he does it♡”
There’s no flash, yet they felt they heard a camera shutter. In a hall where phones were forbidden, someone’s memory clicked a shutter.
“Take a picture!” a friend laughs, framing a rectangle with her fingers from outside the rope.
Momoko throws a peace sign, Iori smiles modestly, and Sora counts 1, 2, 1, 2, 3 and gives a light nod.
At the edge of the bulletin board, small stars line the 4.0/4 row.
The HVAC’s sound becomes the quietest it’s been all day.
Next—nationals.
The pulse still doesn’t stop.
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