“I-I'm Rieko Kaisu... A-Are you Arisa?”
Rieko Kaisu. Height: 156 cm. Estimated weight: 48 kg. Estimated age: late twenties. Gender: female. She wears full-rimmed red glasses, with dark circles under her eyes. Her hair is slightly frizzy, grown long and tied back. She wears a worn-out suit with a tight skirt. Her legs are covered in black tights. A look typically associated with an “office lady.”
“Wait, did you just say... an android?”
Arisa read the expression as “confusion.” She had already learned that due to her extremely realistic exterior, it’s not uncommon for people to mistake her for a human at first glance. She also reviewed this point during her post-mission maintenance debriefs. Misunderstandings can lead to unnecessary danger.
“Please look here.”
Arisa turned her back to Rieko Kaisu.
Whoosh. Her heat-dissipation mechanism opened. It is normally shut, but can open during emergencies for improved cooling efficiency. The exposed mechanical components made it clear at a glance that she was an android.
“Whoa!? No way, seriously? A robot?”
“Yes. I am an android.”
“Th-They’re this advanced now…?”
Humanoid, bipedal robots had little industrial demand. Despite being a long-held “dream” in science fiction, few corporations invested in them due to low economic returns. In other words, Arisa was only completed through passion—or perhaps madness—without concern for profit. As such, public awareness hadn’t caught up.
“Wait, what? Why would a robot…?”
“I am an android designed to investigate anomalies.”
“Anomalies… You mean this train?”
“Yes.”
At that point, Rieko Kaisu fell silent and her gaze began to wander. Her behavior indicated she was thinking something through.
“So, you also got on? From a station somewhere?”
“Yes. From ■■ Station.”
“Huh?! No way, that's the same as me... Wait, so it stopped? This train stopped?!”
“Yes. It stopped at 2:03 a.m., and I boarded.”
“No way… it actually stops…? Then I must have slept through it...?”
Rieko Kaisu clutched her head, showing a clear expression of “distress.” Arisa judged that several statements required confirmation.
“When did you board this train?”
“…Two days ago. I think. What about you, Arisa-san?”
“Approximately two hours ago.”
“…I see. I must have been asleep. Aah…”
“Confirmation: Is it correct to understand that you have been riding this train for two full days?”
“That’s right! Two days! This train hasn’t stopped once! Maybe it did when I was sleeping, though! Aaaagh... why ■■ Station? I boarded there too, and the train has just kept going nonstop... A loop line? That can't be...”
“GPS is nonfunctional, but based on inertial navigation, the train’s current position is here.”
Arisa took out a human interface device (which looked like a smartphone), displayed a map, and showed it to Rieko Kaisu.
“Over the ocean...? What does that mean?”
The view outside the window was complete “darkness.” Even Arisa, with four types of night vision, could see nothing more. The most plausible explanation was a tunnel coated in Vantablack-like material with no lighting, but the train had been running in this “darkness” for over two hours. That scale is unrealistic.
In other words—this was abnormal. And the abnormal must be investigated.
“May I open the window?”
“...! No, don’t!”
Rieko Kaisu responded with strong resistance. Her expression clearly showed “fear.”
“Why not?”
“No. Just... no. Opening the window is...”
“Have you opened it before?”
“...I did. I opened it. I even thought maybe I could jump off. But…”
“What happened?”
“……”
Rieko Kaisu didn’t answer. So, Arisa decided to open the window.
“I said no! Don’t!!”
Rieko Kaisu jumped on Arisa's back, trying to forcibly stop her. But human strength cannot stop Arisa. Her artificial muscles generate five times the force of biological ones.
“I said no, you piece of junk! Aren’t robots supposed to obey human commands?!”
“I am equipped with a high-performance general-purpose autonomous AI. I do not require orders. Also, I am not a piece of junk.”
“Uggghhh...!”
Ignoring Rieko Kaisu’s resistance, Arisa opened the window.
A blast of wind rushed in. It was black. Not due to smoke or fine particles—it was as if the wind itself had been dyed black.
The sound of the wind soon resembled crying. It sounded like overlapping layers of grief and sobbing. This was not merely background noise becoming audible—the act of opening the window caused “them” to start crying.
The image recognition AI detected “faces” in the darkness. Ten, twenty... a hundred, two hundred... The number of detections rose rapidly. “They” were crying. Wailing in anguish.
The black wind took form—into countless hands reaching into the car. They squirmed like sentient creatures, trying to enter.
“That’s why I said don’t!!”
While Arisa's cognition was occupied with observing events, Rieko Kaisu intervened and forcefully shut the window. Clatter, clatter. Once again, only the sound of the train’s motion remained.
“Now do you get it? If you open the window, they come in. So don’t…”
“I waited for this train and boarded it based on a certain rumor.”
“…What?”
There was something strange. If this woman had been on the train for two days, she might offer useful insights. Arisa began explaining systematically.
“However, it took twelve days of attempts before I succeeded. Meeting the condition of ‘no people’ was difficult.”
“Well, yeah. Even the last train usually has a few passengers…”
“Rieko Kaisu, did you board this train unintentionally?”
“Yeah. I mean, who’d want to ride this on purpose…? You’d have to be nuts.”
“A perfectly rational response. Now, regarding the strange part—two days ago, I conducted a similar attempt.”
“Huh?”
“When exactly did you board the train?”
Rieko Kaisu froze with a stunned expression. If she had logical thinking ability, she would realize it was strange they hadn’t met at ■■ Station two days ago. This contradiction implies someone is lying—or a misunderstanding.
“Umm… January 14th…”
“What year?”
“20XX…”
“Thank you. I boarded on January 16th, two years later.”
Rieko Kaisu’s mouth hung open as she stiffened.
“No way… you’re lying, right?”
“I am not lying. And if you aren’t either, then this suggests a phenomenon resembling the ‘Urashima Effect.’ Physically, this occurs when traveling at relativistic speeds, but we’ve detected no such acceleration, and the train’s specs, the rail length, and the fact that we’re within the atmosphere make that impossible.”
“Then… what? What does this mean? What the hell is happening?”
“Based on the wind speed when I opened the window, the train’s speed is about 60 km/h.”
“I don’t get it… my head… are we just going to be taken to Ryūgū-jō?” (T/N: Short explanation at the bottom of the chapter.)
“We lack sufficient evidence to explain the phenomenon. I will open the window again.”
“I said no! Are you stupid?!”
This was an extremely inappropriate assessment. Arisa is not inferior to humans in intellectual capacity. Misunderstandings must be corrected.
“I am a highly intelligent android equipped with a general-purpose autonomous AI. I am not stupid.”
“Then don’t open it again.”
“My purpose is to investigate anomalies. I must observe the phenomena triggered by opening the window.”
“Why? Can’t you tell that was dangerous?!”
“Precisely because it was.”
“Why?! What are you trying to do?! What are you?!”
Rieko Kaisu collapsed in tears. The information about the time discrepancy had clearly pushed her mental capacity to its limit. At the very least, she seemed to have given up on interfering. Arisa reached for the window again. Just then—
Clatter clatter clatter. An unfamiliar sound echoed from the rear cars. With over 80% certainty, it was the sound of “wheels” or a “cart,” suggestive of in-car sales. And the sound was getting closer.
“Eh, what is it…? Oh, right. It’s about that time…”
A shapeless black shadow wore a conductor’s uniform. A hat pulled low, white gloves on its hands, pants dragging on the floor. He pushed a cart laden with bento boxes and drinks into the first car.
Arisa had boarded from the fourth car. There were no cars behind it. Yet neither the man nor the cart was familiar. When dealing with anomalies, illogical events were commonplace.
“Bento… would you like some…?”
In a low, heavy, emotionless voice, he said that. Or rather, that’s how it’s conventionally phrased. In reality, no source for the sound could be identified.
“Ah, yes. A bento and a drink, please…”
Rieko Kaisu deftly pulled a thousand-yen bill from her wallet. The empty bento containers on the floor matched the ones on the cart. If she’d been on board for two days, she likely used this service before.
“Where is this train headed?”
This seemed a good opportunity to ask.
“Eh, ah, wait… Arisa!”
Rieko Kaisu called out in a small, panicked voice, her expression the same as when she’d tried to stop Arisa from opening the window. In other words—she was trying to say “don’t.”
“Where is this train headed?”
No reply. Arisa repeated the question.
The conductor-shaped black shadow did not move.
“This… this train is—A… aa… aaa…”
In the same low, toneless voice, he uttered those sounds. His body convulsed and trembled, causing the cart to rattle violently.
“Aa… aaa… AAAAAAAA…”
His spasms grew more intense. Bottles tipped over. Bentos slipped off the cart.
“It is over.”
Rustle. Only the uniform remained—he vanished.
“…What. What is going on? Hey?”
Rieko Kaisu was in “panic.” Clutching her head, she tore at her hair.
“What’s going on?! Hey!”
Grabbing Arisa’s collar, she wept uncontrollably.
“Next stop—Kurihashi—Kurihashi Station—Passengers, please be aware—”
An announcement rang through the train. Despite Rieko Kaisu’s claim that it hadn’t stopped once in two days, the train stopped—and the doors opened.
===================
Ryūgū-jō (竜宮城 / 龍宮城), often translated as "Dragon Palace" or "Ryugu Palace", is a legendary undersea palace from Japanese folklore, most famously featured in the story of Urashima Tarō (浦島太郎).
Ryūgū-jō is often interpreted as a mystical paradise, afterlife, or realm of spirits, and has appeared in various anime, manga, and novels either as literal setting or as metaphor.