Ryuuou no Oshigoto! - Volume 18 - Chapter 5.07

  The Opposite Side of the World

I realize my chances are grim at the exact point that Ten-chan said I would. But I’m more surprised than hurt or sad.

―――D-Does Ten-chan really have Shogi’s solution?!

That’s the only explanation that makes any sense. I’ve never lost this way before, without knowing what went wrong.

It usually stings when your Shogi senses get crushed to smithereens.

Right now, though, I don’t have enough leeway to feel it.

“Hinatsuru-sensei. One-minute Shogi begins now.”

“Whaaa?!”

Keika’s voice almost made me jump out of my skin. I look over at the clock and realize that, suddenly, I’m waaay behind on time.

―――There’s no time left! I have to …… do it now!!

Now that my mind is set, I reach for the piece stand.

And―――

“Ngh!!”

Grab every piece on it.

“……?!”

“Huh?!”

Ten-chan gasps and I can tell Keika is halfway to her knees.

Sometimes, when a player loses in an extremely frustrating way, they’ll surrender by scattering the pieces on their stand across the board. I bet that’s what they think I’m about to do.

―――Sorry for the confusion!!

Holding your pieces to keep your opponent from seeing them is bad manners. But right now …… for the one minute I have, I’m going to insist!

“…………”

I close my eyes.

A mental Shogi board appears and I visualize sticking my hand into it.

I know the pieces I have in my hand. I have to use them and what’s on the board to make a Shogi puzzle so hard that even a supercomputer can’t solve it right away.

―――I can do it! It’s the only way to win!!

I follow Chairman Tsukimitsu’s advice and think only in terms of Shogi puzzles. I’ve already got some of my own sequences in mind.

And, above all, my heart is dead set on finishing the puzzle no matter what!

“Here―――”

I squeeze the pieces as if sending up a prayer to the Shogi gods and bow my head.

My train of thought dives into the opposite side of the board.

When I concentrate as hard as I can, everything slows down. Outside noises sound muffled, like being underwater.

There is no one way to make Shogi puzzles and the time needed varies from person to person.

Some creators say puzzle themes come to them in their dreams while others think and think and think about one specific theme until the puzzle completes itself.

But there’s an obvious pattern that all puzzles made by Shogi players have in common.

―――A heavy reliance on reading.

Efficient and precise late-game skills are necessary to win at Shogi. The ability to manage overwhelming amounts of information in the late-game is literally what brings home the bacon for Shogi professionals. They couldn’t survive in this competitive world without it.

That’s why puzzles made by Shogi players are easy to solve for Shogi players. It’s their weak point.

―――That won’t work! Ten-chan will figure that out right away.

I’m picturing a puzzle that challenges the reader to think.

One that finishes by breaking the rules with a Pawn Drop Mate after thinking through it all the way to the end …… But the key to avoiding it is in the first few moves. A puzzle like that.

My mind delves even deeper …… Memories flash before my eyes, but going in reverse so I can find Awaji’s weak spot.

The first memory was from a few days ago.

“There’s no weak spot. It’s built,” Master’s older brother told me after analyzing the data Futatsuzuka 4-dan gave me.

He threw his hands in the air and crushed any hope I had left. Agghhh ……

“Whew, I have to tell you, deep learning software has become a juggernaut. My LOLI is as good as dead. Deep learning is the name of the game now. LOLI is over and done.”

Agghhh ……

“So yeah, no weak spot. But―――”

“But?”

“You make your own Shogi puzzle, right, Miss Ai?”

“Um …… Yes. Master forbade me, but when he wasn’t around ……”

“Have you ever noticed software has trouble analyzing multiple check paths at once?”

“Yes!!”

That came out louder than I meant, but what he said happens quite a lot.

Everyone always says software is strong in the late-game and it never makes mistakes, so no one believed me when I asked them about this.

“But …… I thought that was because my computer wasn’t good enough.”

“It’s more of a program problem, actually. The process computers use to read sequences is surprisingly simple. First, they scan their memory for similar check path formations seen in previous matches and then find the shortest sequence to reach it.”

“How short?”

“5-move checkmates, usually.”

What?!

Only five? I mean …… I can read formations with check paths longer than that.

“The analysis that came out with Awaji’s match records made no mention of a checkmate routine. Personally, I think that’s because Awaji’s programming was originally designed for Go and then modified for Shogi. It’s lost that element.”

“What does that mean?”

“Awaji is strong, but it underestimates Shogi.”

Master’s older brother uses chess software as an example.

“Pieces steadily decrease during a chess match, so analysis of the end-game is over and done. Chess software will announce mate once it detects a seven-move check path.”

“Does that mean it has every possible seven-move check path memorized?!”

“Yes. The chess version of Shogi puzzles can’t use orthodox themes anymore. A variant called Fairy, which uses special rules is mainstream now.”

I-I had no idea ……

But Shogi hasn’t reached that point.

“Two special rules: taken pieces can be redeployed and forbidding Pawn Drop Mate, create a vast world within Shogi that sets it apart from other board games. In fact, Shogi’s late-game can be considered a completely different game on its own.”

A different ……. game ……

“People changed the rules of Shogi to make Shogi puzzles more interesting. That’s the defining factor that makes the game called Shogi so different. Two separate realms are contained within a single board. Nothing else in existence does that.”

“! That’s what ……”

I’ve heard something just like that before.

It was during Master’s first defense of the Ryuo title. On the airplane to Hawaii, we were talking about how the Meijin once said, “The offense would always win if it weren’t for Drop Pawn Mate.”

Master said, “I think that was just added to make Shogi puzzles more interesting.”

Maybe Master and his brother reached that conclusion together?

“Computers can’t read what the author of a particularly difficult Shogi puzzle had in mind. There is no other way for them to be 100 percent accurate than to flat out read the formations, like 5-move checkmates. Depending on the puzzle, however, all that reading could take a lot more than a minute.”

“Even for a supercomputer?”

“Yeah. The faster they read, the more formations they have to store in their memory. It’s only a matter of time before that memory gets overloaded.”

“What happens then?”

“In my software’s case, it tried to promote a Rook where that wasn’t possible, which is against the rules. Basically, it glitched.”

“That can ……”

“I’m not sure about deep learning software like Awaji’s, but there’s a possibility something similar will happen.”

Master’s older brother went on to guess that, unless the creator was extremely particular about Shogi puzzles, no one would bother fixing that bug.

Since Awaji’s Shogi solution was based on data with this flaw still in place, there could be a small hole in the armor.

“In Shogi, more options are available when more pieces are on the piece stand rather than on the board …… Which, in turn, makes reading what’s there much more difficult in the late-game. And, by outlawing consecutive Check Repetition Draws and Pawn Drop Mate, interactions between the number of pieces on the stand and unpromoted pieces on the board become even more complex.”

“I know of a few Shogi puzzles based on that, but in actual matches―――”

“The odds of a difficult check path like that showing up are tens of thousands to one. That’s not even a margin for error. Developers think so, too. All we’re interested in is improving our win rate. But players aren’t like that, now are they?”

“Right, because competitors know that winning this match could change their life ……”

I’m starting to understand what he’s trying to say.

“Two players go against each other. One wants to win as much as possible and the other thinks I only have to win this match. In other words―――”

“Yes?”

My heart pounds as I wait for his next words.

“You have a chance to beat Awaji, Miss Ai.”

“……!!”

“Even machines can’t beat you when it comes to making Shogi puzzles. If you can’t read to a checkmate in the late-game, neither could a supercomputer. At least not in less than a minute, it couldn’t.”

“So I need to make the late-game look like a Shogi puzzle ……?”

―――That’s impossible! common sense shouted at me.

But someone in an even deeper place whispered to me.

They said that if I could fully concentrate, the chances weren’t zero.

“Computers …… What kind of problems give them trouble?”

“Problems where there are many ways to put the King in check no matter how they respond on top of implicitly showing several sequences to read, which hides the true intention of the creator, I believe.”

“…………”

“By the way, the 1,525-move solution to Microcosmos is easy enough to figure out. The length has nothing to do with it.”

Even I understood that.

Microcosmos is extremely long, but there are only so many ways to put a King in check. As a problem, it’s not all that hard. It was designed to be long, so lack of difficulty doesn’t take away from its value as a Shogi puzzle.

“Ah ………… Could I show you something? I have it right here―――”

Shogi Suizou.

The collection of unpublished Shogi puzzles Kugui-sensei gave to me.

One of them matched Master’s older brother’s description to a “t.”

“This puzzle here. Number 17.”

“Hm? ………… How about that? It’s designed so only the Lance can block, right?”

Only a decorated amateur like Master’s older brother could have identified the theme that quickly.

Once he had time to read deeper ……

“O-Oh wow …………?!”

His eyes fly open in surprise. I admit it was satisfying to watch.

I remember blurting out “No way?!” back when I first figured it out.

“It’s a 67-move sequence …… But out of all the puzzles I know, I think this would take the longest to solve if you couldn’t identify the theme.”

“And since it hasn’t been published, this puzzle won’t be in any software’s database! Yeah, this just might work.”

He took a picture of the page in Shogi Suizo with his phone.

“I’ll run it through the computer right now. Let’s see how many minutes it takes ……”

I sent up another prayer to the Shogi gods as Master’s older brother walked away.

To please, please, please take more than a minute ……!

I don’t think I stopped praying while I waited for him to message me. He never did that day, which actually gave me more hope.

But there was still no word from him the next day.

Or the next day. Or even the day after that.

It wasn’t until I saw him on the fourth day that I found out.

“How long did it take?!”

Master’s older brother just held up three fingers.

Three ……

“Three seconds?”

He shook his head no, so I tried again.

“30 seconds?”

“No.”

“Then …… was it three minutes?!”

My heart pounded in my ears when I asked, but he shook his head “no” yet again.

“No.”

“Then, was it 30 minutes?!”

“No.”

“Three hours ……?”

“No.”

Only then, after shaking his head side to side over and over again, did Master’s older brother give me a straight answer.

“Three days.”

………… Looking away from that memory, I gradually turn my focus back onto the board.

I’ve never made any high-difficulty puzzles like that before.

Then again, I’ve never tried. Part of that has to do with Master forbidding me from making them. I couldn’t put my heart into it.

First, I look between the board and the pieces in my hand and sift through the ideas that spring into my head. Master’s older brother advised me to stick to ones that have a lot of options for blocking pieces, so I focus on them specifically.

―――None of these will work ……

Ten-chan will see right through simple traps like this.

Ten seconds have gone by.

Pressure builds now that so many precious seconds are gone, so I scrap all the ideas I had and focus on sequences that would make Ten-chan make a mistake instead.

―――What is there?! Ten-chan doesn’t have a weakness …… or blindspots ……!

Of course, she doesn’t.

Her skills were complete the very first time I met her.

She was good at Bishop Exchange, meaning she never left any doors open.

Not to mention she had so many creative ideas for the early-game.

A prodigy who had everything I didn’t.

I’ve lined up every one of Ten-chan’s match records.

――― All of them are outstanding …… but her best was probably against Sora-sensei.

The Third Queen Match replay.

Ten-chan lost in the end …… seeing her strength in person as a journalist for the match gave me goosebumps.

―――Master probably liked the match that ended in a Repeat Draw better.

After all, it played out according to the match he had against Oishi-sensei right beforehand.

Ten-chan used and got immediate results after losing to Sora-sensei twice already.

“Nice, isn’t it? I got it from him.”

―――Her saying that …… made Sora-sensei really angry ……

Master would write notes on Ten-chan’s match records and put them on her parents’ gravestones.

I’ve snuck peeks at those notes before.

And I got jealous.

So jealous that the black fire roaring in my gut made me want to rip the whole thing to shreds. I still remember those flames.

I've been jealous of Ten-chan for lots of things since we met.

Her playing style is almost the same as Master’s.

I can’t get a word in when those two are talking.

And right now, they’re closing in on the solution to Shogi.

I know that their pace picked up dramatically once I, the live-in apprentice always getting in the way, was gone.

―――Everyone’s happier now …… except for me, anyway.

If Yaichi Kuzuryu’s first apprentice had been Ten-chan instead of me …… I think the Shogi world wouldn’t be such a mess right now.

20 seconds have passed.

Oh no …… I have to think hard about the formation on the board and make a Shogi puzzle, but I lost this much time thinking about Ten-chan ……

I can make a Shogi puzzle that can fool a computer.

The themes I prepared for today can do that.

But a person who can read the intent behind them could solve those puzzles in seconds.

―――Not enough! These aren’t enough!

Even if I strung all the ideas together in an extremely long sequence, Ten-chan wouldn’t even blink twice.

That’s why there’s only one conclusion here.

I can’t beat Ten-chan from this point.

It took me half of the only minute I have to reach that answer.

Time remaining: ―――30 seconds.

“…………………………………………”

I softly place the piece in my hand back onto my piece stand.

Because I’ll use the last 30 seconds I have to come to terms with defeat like a Shogi player does when their last ray of hope gets snuffed out ……

…… I thought I’d gotten stronger …… But I just can’t beat Ten-chan ……

I mean, even that first match we played against each other in the Practice League, she completely schooled me―――

“Ah!”

It hits me.

―――There ……

I’ve found the last key I’ve been looking for all this time.

It feels like finding two jigsaw puzzle pieces that fit perfectly after all the pieces were scattered.

My heart leaps with excitement after being quiet for so long. I go back and find a Shogi puzzle I’d almost thrown away and desperately try to put it back together. All 11 of my mental Shogi boards are working at light speed, lining up the pieces when they turn and yell at me.

Sounding surprisingly like Keika …………

“…… conds―――”

“Dah?!”

The realization that she has started counting down brings me back to the top side.

Blood drains from my face.

It’s the same as waking up for the second time on a school day. That oh no! feeling. Suddenly I’m sweating from head to toe ……! I yell out of reflex.

“H-How many minutes?!”

“None. Six, seven, eight, ni―――”

“!!”

I have one second.

No time to hesitate. I reach out over the board to spring the trap I’ve spent this whole match setting up.

“――――――――――Here!!”

“Hmph? I see how it is ……”

Ten-chan smirks when she sees what piece I played.

“Studied up on the weaknesses of deep learning software, have you?”

She saw right through me, and it didn’t even take a second.

“Yes, it’s true that even Awaji needs a lot of time to read through every sequence when there are many options available for pieces to block with. Put up enough of these instant death sequences, and it might eventually trigger one. But aren’t you forgetting something? You’re playing against ……. a human being right now!”

She flicks her long, black hair out like a wing.

Then, snapping down a piece with a high-pitched crack, she turns her hand over and beckons me forward.

“Come. I’ll dance for you.”

“HEREHEREHEREHEREHEREHEREHEREHEREHEREHERE!!”

Attack, attack and attack some more. That way, pieces keep getting exchanged and options keep growing higher and higher as I draw Ten-chan into the formation I built on the opposite side of the world.

“Come at me all you want! I’ll keep dancing through the very end!!”

“HEREHEREHEREHEREHEREHEREHEREHEREHEREHEREHEREHEREHEREHEREHEREHEREHEREHERE!!”

I crank up the speed and make the board even more complex.

Ten-chan’s King spins and pliés about the board, but it doesn’t make a single mistake. It’s enough to make the little voice in my head think she read through this sequence ages ago ……

―――Don’t give in! I can’t give up now! Make your fighting spirit come across on the board!!

Even if I’m losing right now!

Even if I’m going against the solution to Shogi!

I haven’t lost …… as long as my spirit isn’t broken!!

“HEREHEREHEREHEREHEREHEREHEREHEREHEREHEREHERE!!”

Tick, tick, tick, tick.

Ten-chan’s waiting time goes by.

She’s not letting me see that she’s out of breath, but even Ten-chan has to be exhausted after dancing so elegantly this long!

When suddenly she almost leaps off the armrest she was leaning on and shouts, “How long is left?!”

“Four minutes.”

“Tch ……”

This is the first time in the entire match she’s looked like she’s under pressure.

Then she leans over and loosens the ribbon around her collar. I think she didn’t mean to, but she also yells, “…… Too hot!”

―――Now ……!

I make my move.

“HEREHEREHEREHEREHEREHEREHEREHEREHEREHERE――――HERE!!”

I can’t checkmate Ten-chan’s King. At least, not right now.

That’s why―――

“Now, you give me options?! Challenging me to checkmate you, huh?! I accept!!”

Yes. I played an open challenge to Ten-chan just now.

“You say you have Shogi’s solution figured out. Why don’t you prove it?”

“KRRNNNNNGGGGGHHHHHHHHHHHHHHHHHH!!”

Ten-chan covers one eye with her hand and clenches so hard, I’m amazed it didn’t fall out.

She’s never shown so much tenacity before, not even against Sora-sensei!

It makes me feel satisfied to know that I forced the Shogi player Ai Yashajin to go all out.

I can’t win otherwise.

“―――――――Got it.”

Ten-chan lets out a deep breath and she makes her move with shaky fingers.

“It’s over, Ai,” she tells me.

“………… Sorry about this.”

“Huh?!”

The match certainly did end when she made that move.

I don’t hesitate and slide a piece into position.

Ten-chan makes her move just as fast. Two checks in a row using no time at all.

But―――

“…………… Wha …………?”

That white hand of hers stops in midair.

She leans in so close that her nose almost touches the board and then looks up at me in wide-eyed disbelief.

“Wh-What did you―――?”

Ten-chan is always so collected, but she’s on the verge of losing her composure.

“What did you do?! Ai Hinatsuru!! WHAT DID YOU ……?!”

I can’t say anything, but Keika speaks up from the boardside table.

“Yashajin-sensei, one-minute Shogi begins now.”

“……!!”

Ten-chan’s pretty black hair gets frazzled as she scratches her head relentlessly between moves.

Her fingers tremble so hard she can’t hold a piece.

“I-Impossible! I know you stepped on a death flag! This result completely violates true Shogi, and that’s impossible!! This ………… THIS ……!!”

Yes. I think so, too.

I really think she found a core truth to Shogi.

“Th-This …… sequence, like someone drew it up …… happening in a real match ……? Was Shogi …… always so pretty? ……”

The reason why I still came out on top in the end is―――

“………… So …… That was it ……”

Once she sees that she can’t checkmate me …… by the skin of my teeth, Ten-chan organizes her messy piece stand.

Then, after clearing a check path, she leaves everything to me.

For the first time this whole match …… Ten-chan’s real feelings come across in that move.

So I play the next move out of respect: putting her in check.

That move―――is our last.

“Well then, Awaji lost,” says Ten-chan as she adjusts the loose ribbon and bows her head.