Our exploration of the labyrinth was proceeding with surprising ease.
The white radiance of the Light Rod stretched deep into the corridor, clearly illuminating the damp rock walls and the gravel beneath our feet. Visibility was excellent, and we hadn't encountered a single monster ambush. In fact, because most monsters tended to loathe the light and kept their distance, our combat encounters had been kept to a minimum so far.
Unlike my time in the Primal Labyrinth, this was a remarkably peaceful expedition.
We walked through the passage in a line: Rio in the lead, followed by Lene, and finally myself.
Technically, Lene should have been leading the way as our vanguard, but given the sheer amount of light, we figured we could react to any threat the moment it appeared. Thus, she had allowed Rio to take the lead for the time being.
(Well, she does seem a bit lax in her vigilance for someone walking point, though...)
Rio, at the head of our line, was casting her gaze downward at her hands rather than looking at the path ahead.
She was clutching an unfamiliar magic tool.
It was a thin, plate-like object that looked remarkably like a tablet from my previous life. Rio supported it with one hand while using the other to tap, flick, and occasionally slide her fingers across the surface.
The screen appeared to be displaying—a map, I presumed?
Lines drawn in faint light were slowly extending across the surface of the plate-shaped device.
"...You're using something very convenient again, aren't you?"
When I inadvertently muttered this, Rio, who seemed to have overheard me, looked back over her shoulder.
Her smile deepened as she held up the magic tool as if to show it off.
"Heh-heh! Impressive, right? It's a magic tool that records the labyrinth's terrain! It keeps track of every corridor and room we've walked through so far!"
As she spoke with pride, Rio pointed at the screen.
A map was indeed being rendered there, and its shape was familiar. If I wasn't mistaken, it was an exact replica of the path we had been traveling until just a moment ago.
When I gave her an honest "That's incredible," Rio let out a pleased hum.
"Labyrinths can change their structure, and there are so many identical-looking passages, right? That's why most adventurers make maps so they don't get lost—but doing it by hand is such a pain, isn't it?"
As Rio shrugged, both Lene and I let out wry smiles.
Now that she mentioned it, she was right.
It wasn't a topic we "nobles," who rarely had opportunities to enter labyrinths, were very familiar with, but making a map was considered a Basic Adventurer Skill. While the game tended to skip over those details, in reality, it was apparently a grueling, back-breaking task.
I remembered Yuu and Ciel grumbling in the past that "map-making is the most annoying part of the job."
"—So, I decided to automate it!"
"...You make it sound so simple."
It wasn't the kind of magic tool one could just whip up easily just because a task was "annoying." The fact that she could create it as if it were nothing proved that Rio really did possess the talent worthy of being called a "Genius," just as Albert had said.
"It is a remarkably convenient magic tool, isn't it? Is this also a prototype?" Lene asked.
"Yeah. I think there are still plenty of areas to improve. First, I need to reduce the cost of the materials. I want as many people as possible to use it eventually, so I absolutely have to iron out those details."
As she spoke, Rio lightly tapped the magic tool in her hand.
"Since this is just a prototype, I used magic stones a bit extravagantly. It's not suited for mass production yet... well, the mechanism itself is already finished, though."
With a soft beep, a magic stone glowed faintly.
"Next, I want to improve the sensing range. Right now, it can only record the paths we've actually stepped on, but don't you think it would be great if it could read a wider area?"
"You mean so it could predict the layout of the labyrinth ahead of time?"
"Exactly!" Rio replied, her fingers dancing playfully across the screen. "And in the future, I want to add a Sharing Function."
"Sharing?"
"Yep!" Rio looked back and gave us a wide, mischievous grin. "That way, a map made by an earlier explorer could be viewed by those who come after them! Just knowing the layout or what kind of monsters are ahead would be a huge help, right?"
Seeing Rio's vibrant, joyful expression, Lene and I couldn't help but smile along with her.
"...You really look happy when you talk about your inventions."
When I said that, Rio blinked in surprise for a moment. But a split second later, she gave me a broad, confident grin.
"Well, of course I am!"
Her voice was devoid of any doubt.
"I mean, my inventions might save someone's life, or make their daily routines or explorations a little bit easier. Just imagining that... it just makes me so, so happy. Don't you feel the same?"
Rio held up the magic tool and spoke with a beaming smile.
To create something that helps someone else.
To find joy in the resulting smiles of others.
That was likely the most honest and noble sentiment an engineer could have.
(I think I understand why Albert wanted to brag about her.)
Her imagination and the technical skill to realize it were certainly extraordinary. But more than that—this girl was pure. She genuinely wanted her inventions to be useful to the world, even as she enjoyed the process of creating them.
That was why that great man spoke of her with such pride. His granddaughter was, without a doubt, a genius.
(—And yet, the 'CHOICE//MAZE scenario' saw fit to cut her from the world...)
I watched Rio walking beside me with her radiant smile, my thoughts turning dark.
The items Rio created were undeniably convenient. The Light Rod, the Auto-mapping Map, the Teleportation Device... and those were likely only a fraction of what she was capable of.
But what would happen if all of those were released into the world?
It wouldn't just save students; it might even save the heroines who were destined to die.
(—The scenario would never allow that.)
In the world of CHOICE//MAZE, which forced the player to decide "which to choose and which to abandon," these were game-breakingly powerful magic tools. They had the potential to create a Third Choice where everyone survived. There was no way the Production Team would leave such a disruptive existence alone.
That was why she was only mentioned by name.
The lore dictated that she had already passed away by the time the main story began. All the game ever mentioned was the tragedy of a Genius Inventor who died young, leaving behind blueprints and ideas that benefited later generations of adventurers.
But, if I looked at it from another perspective...
If I could save her, the entire narrative would shift.
I might be able to save more students who were fated to die. I might be able to offer a different path to those who had no choice but to give up. I might be able to reach a conclusion that was never meant to exist in the original work.
Rio Krausel's survival itself could be the "Third Choice" for this entire world.
(...That's all the more reason I can't let her go.)
Even if the original work discarded her for its own convenience. Even if the scenario judged her to be an "obstacle."
None of that was a reason to let the girl in front of me die.
Besides—I already knew too much about her.
The way she looked when she talked about her work. The way her voice filled with joy when she thought about helping others. The way she respected her grandfather more than anyone and deeply regretted their argument.
I knew it all.
(Then...)
Even if it was against the "proper flow" of the story. Even if it was inconvenient for this world's logic.
None of that mattered.
As her friend—I would protect her.
I would protect her life and her talent. And more than anything, I would protect that future where she could smile while inventing things for the sake of others.
While I was lost in these thoughts, we had apparently progressed a fair distance through the corridor. Having finished our conversation, Rio faced forward again.
"Alright, let's get back to it!"
With a cheerful tone, she resumed her lead. Lene and I exchanged a nod and followed. The passage remained quiet, save for the sound of dripping water and our boots crunching on the gravel.
We continued like that for a while until—
"Oh!"
Rio let out a small gasp. Her eyes were fixed on the far end of the corridor.
"—Wait right there!"
Without another word, she dashed forward.
"H-Hey, Rio!?"
I called out, startled by her sudden movement. But she didn't look back, her footsteps light as she ran toward the edge of the Light Rod's reach.
Lene and I hurried after her, wondering what had happened. We found Rio crouching in front of a small alcove hidden in the shadow of a rock wall.
"Look, look!"
With a smile as bright as a blooming flower, she pointed.
I followed her finger to find a small wooden box sitting alone in the hollow.
Actually, calling it a "wooden box" might have been a stretch. The wood was cracked and blackened with moisture, with patches of green moss clinging to the surface. It was half-buried in the dirt and rock, appearing almost as if it had grown out of the labyrinth itself.
—A Labyrinth Treasure Chest.
A staple of dungeon crawling that I had seen countless times on a screen. And now, it was sitting right before my eyes.