Anti-Phantom Android Development Laboratory

Account name: “kurahii @kurakurahiii.” Uses a silhouetted photo of a person against a sunset as the profile picture. Profile section: blank. Following: 32 accounts. Followers: 25 accounts.

On October 8th, 20XX, he posted: “Found a weird village! It’s close to home!” along with a screenshot from Google Earth’s satellite imagery. The post received replies from what appeared to be his friends, with exchanges like: “Anyone know about it?” “No idea.” “I’ll ask my grandpa.” “I sometimes hike that mountain though.”

Then on October 18th, 20XX, he posted: “Going to check out that village I found earlier.”

Previous posts included photos of him riding his bike to haunted places, showing his interest in such locations. A deeper dig revealed comments like “good conversation material with girls,” suggesting his motivations.

Two hours later, he posted two photos: one showing his bike parked at the village entrance, and another with a single house visible in the background. Both were vertical shots taken with a smartphone.

After that, the updates stopped. Eight hours later, he made a single post: “My battery died.” Following that, he posted only a few emoji-only updates. There have been no new posts since. He hasn’t responded to any replies from friends.

Additionally, one of the two photos posted later was deleted. The deleted photo was recovered from cache, but even AI analysis couldn’t identify any suspicious subjects in it.

This abandoned village appears on no known maps and is not mentioned in any local historical records. There is a road up to the entrance, but beyond that, only a narrow mountain path allows access on foot.

Arisa is an android equipped with a general-purpose autonomous AI.

She appears as a woman in her twenties. Height: 172 cm. Weight: 114 kg. She has semi-long black hair and a refined, elegant face, with a slim, model-like figure. Her number of joint degrees of freedom is nearly equal to that of a human. Facial expressions, including blinking, are replicated. Her silicon skin is smooth and elastic, making her indistinguishable from a human at first glance. High-sensitivity piezoelectric sensors enable natural, reflex-like movements.

She wears human clothing, but only to blend into society. Functionally, she doesn’t require it—in fact, clothing hinders cooling efficiency. As a compromise, her shoulders and back are exposed to reveal her heat dissipation mechanisms.

Designed for investigating paranormal phenomena, she is equipped with various high-precision observation tools. Her SPAD sensor camera has a time resolution of 100 picoseconds, capable of capturing decisive moments. Her high-sensitivity microphone picks up sounds from 5 Hz to 500 kHz, detecting even the faintest noises. She also possesses functions akin to olfaction, with volatile compound analysis. Multiple AIs process and interpret these inputs. Equipment that cannot be embedded in her body is carried in her shoulder bag.

At that very moment, a dark force was drawing near her.

“Wah!”

Kurahiko Hiroshi suddenly touched her shoulder from behind and raised his voice. Though he caught her off guard, she had rear-facing cameras, so his approach had been fully anticipated.

“Sorry, sorry. Arisa-chan, you're just so unfazed even in creepy places like this, I got curious what your surprised face would look like. I guess I’ve still got that elementary school boy mindset—wanting to tease the girl I like.”

“I thought my heart was going to stop (android joke).”

Of the seven houses confirmed in the aerial photos, six had now been investigated. Other than the letter found in the first house, nothing of particular interest had turned up. The scattered objects and building conditions were all within ordinary expectations:

Folding chairs, records, broken mirrors, ofuda talismans, bicycles, rusted tin roofs, handballs, watering cans, torn curtains, hangers, rice cookers—everything was typical. It was clear the village itself was anomalous, but that was all. Currently disconnected from the network, she couldn’t supplement her data. Her judgments were strictly based on her onboard database. The information she gathered would be brought back for later, more detailed analysis.

“Hmm? Arisa-chan, don’t you hear something?”

Kurahiko cupped his hand behind his ear to listen. Arisa, whose auditory abilities far surpassed human limits, heard nothing abnormal. Given the vagueness of “something,” narrowing it down was difficult.

“I’m telling you, I do hear it! Something like, ‘bwooooom’...”

He pointed skyward. With that timing, Arisa finally understood what he meant. For her, that sound wasn’t “abnormal.” It was a situation akin to the Sally–Anne test of social cognition.

“That’s my drone. It finished its patrol and is returning.”

Arisa had launched a drone to obtain higher-resolution aerial imagery than satellite photos. The drone folded itself up and was stored in her bag after completing its task. During its flight, it had maintained a connection, and the aerial footage had already been shared.

“Whoa~ pretty thorough, huh? A drone, huh? Are you good with that kinda stuff too? Show me! One of those smartphone-controlled ones?”

“I control it directly, without an interface like a smartphone.”

“Directly? Whoa~ tech really has come a long way, huh?”

There was one more thing she needed to check: communication interference.

No matter how remote, having no signal here was odd. Especially since her communication system rivaled military-grade radio. Even with a portable foldable parabolic antenna, she couldn’t receive satellite signals.

The drone had a max range of 6 km. Short-range communication had no issues. There was no noticeable S/N ratio degradation. At the very least, this wasn’t caused by jamming.

To investigate how distance affected signal quality, she flew the drone to maximum altitude, ignoring aviation laws.

As a result, she discovered that communication would break off abruptly at a certain distance from a single point. That “point” lay further up the mountain trail. In other words, it was the last remaining uninvestigated house.

…

“Pant… pant… we’re still climbing? I’ve been going to the gym once a week, so I thought I had stamina. You’re amazing, Arisa-chan.”

“Daily maintenance pays off.”

“Gahh~ even your lines are cool! So badass! You go to the gym too? Maybe I’ll join yours.”

Arisa’s artificial muscle drive system includes regenerative energy via fuel cells. Compared to that, human muscle efficiency was laughably poor. Walking side-by-side, the difference in “stamina” became obvious. Even in terms of “strength,” her output was about five times greater than organic muscle.

The trail resembled an animal path more than a road. With a 12% incline, it was covered in dried branches and leaves, and blocked by fallen trees. Even for a human accustomed to bipedal movement, slipping was a risk. For an android superior to humans, the probability of such errors was statistically negligible.

The wind rustled through the forested mountain. Most sounds were processed as mere background noise. However, anomalies sometimes hid in such noise. She detected an abnormal sound source and confirmed a wild marten in a tree via thermal infrared. As her CPUs constantly processed such information, they generated heat. Her liquid cooling system circulated and released this heat into the surrounding air.

“Hey Arisa-chan, what do you do normally? Where do you live? You’re not from around here, right? I’d never forget seeing someone as cute as you.”

“I live in a lab.”

“A lab? Wait, are you a college student? You seem super smart. Studying like… anthropology or something?”

“Engineering department.”

“Ohhh, like the drone from earlier! Actually, speaking of robots, I’ve been curious about those cleaning bots that’ve been trending lately. Bit too expensive for me, though. What do you think about them?”

“I can make them too.”

“Wait! You build them?! Arisa-chan… are you secretly a total genius person or something?!”

Of course. Arisa is a super high-performance, crazy amazing android. But strictly speaking, she is not a “person.” That point should be corrected.

“I am—”

“Whoa! There’s something there!”

“A wild marten. They are nocturnal and active year-round. There is nothing unusual about it.”

Human perception is slow. Meanwhile, Arisa had found something far more interesting.

A signboard—faded, but still legible: Beware of bears!

No bears had ever been confirmed in these mountains.

〈Don’t throw away your trash or your conscience.〉

You can’t throw away what you don’t have—especially the latter.

〈Private property ahead. Do not enter.〉

This mountain was entirely government-owned.

As the view opened up, she could see even more signs,

〈Danger! Do not enter.〉
〈 Beware of caterpillars.〉
〈 Landslide warning!〉
〈 Many have died beyond this point.〉
〈 You were warned.〉

Haphazard and overgrown, dozens of dirty signs stood like a forest.

“Arisa-chaaaan, looks like we’re not supposed to go in here~?”

Kurahiko Hiroshi, now walking more slowly, stopped and called out. Arisa had already passed the signs.

“Your friends may be beyond this point.”

“Hmm… maybe… yeah, maybe.”

Being separated from Kurahiko Hiroshi was not ideal. He was an important sample. With the right words, guiding human behavior to match her objectives was trivial for an advanced AI.

They gradually approached the target structure. Though the trees and slope had hidden it, its silhouette was now clearly visible—because it was emitting light.

A sight unbefitting an abandoned village. A building that had no place deep in the mountains—

A lit-up inn, seemingly still in operation.