I'm Z.

  I'm not someone who can't handle being alone, but when you're stuck in prolonged isolation with no idea if you'll ever return to civilized society, even I can't think with a normal mindset.

  This basement has too few clues, and not many items that could spark positive associations. Before long, my mind started wandering aimlessly, like watching a documentary on the cosmos. In a way, I'm just like those bored folks who forget their phone in the bathroom and end up pondering the meaning of life or the end of the universe. It's not that I don't want to properly reason out how to escape this place—who can blame me when I'm basically stuck on the toilet right now.

  But after a while, as I lay sprawled on the floor like a fish washed up on the beach, trying to find some revelation in the patterns of the concrete ceiling, a spark of insight suddenly flashed in my consciousness.

  I bolted upright, rummaging through my memories for clues, mulling over the inspiration I'd just gotten.

  I think I've figured out the pattern behind the cave's disappearances and appearances.

  The cave's vanishing and emerging likely follow the same set of rules. At first, I thought knowing why it disappears wasn't enough—that was my mistake. Agent Kong and the female demon hunter might have assumed the cave's formation was outside the ritual circle, but no, the answer is the ritual circle itself.

  Agent Kong once mentioned that the ritual circle's purpose was to "open certain alternate spaces overlapping with real spacetime," and it was deemed a failure because "it lacked the final magical symbols."

  I'm not entirely sure how magical symbols work, but since the cave appeared, it means the missing symbols were somehow completed by accident.

  So, what exactly filled in those missing symbols in the ritual circle?

  Right now, my suspect is that black shag rug.

  More precisely, the letter patterns on the black shag rug.

  It's not that the letters are equivalent to magical symbols, but perhaps the lines forming the letters coincidentally matched the requirements for the symbols. And I have circumstantial evidence to back this up.

  Let's recall the situations when the cave appeared and disappeared. Every time Chang'an and I went through the motion of covering and uncovering the black shag rug, the cave's state switched between appearing and vanishing.

  This morning, Chang'an and I uncovered the rug, and the cave appeared; then we covered it, and uncovered it again in front of Agent Kong, and the cave disappeared; later in the afternoon, Agent Kong casually covered the rug while inspecting the room alone, and when I came back at night and uncovered it, the cave appeared.

  The same thing happened the night before last, when Chang'an first spotted the cave. After uncovering the rug the first time and discovering the cave, he called the police, then "uncovered it again" in front of them—he specifically mentioned "uncovering it again" when telling me—which means he must have covered it back up before the police arrived.

  Why did he cover it in the meantime? Because he was scared. Today, when he was with me, he said he worried there might be something nasty still lurking below the cave, so the night before last, he chose to seal it with the wooden lid and the rug together.

  In all these instances, the black shag rug acted like a "switch," directly linked to every change.

  Is my reasoning correct? Can I just confirm it like that?

  No, hold on, hold on... I've missed a crucial detail!

  That's why the cave's entrance disappeared after I entered it.

  If the cave's state only changes after covering it with the black shag rug, then the cave shouldn't have vanished on its own after I went in.

  Unless... unless after I entered, some "unidentified person" sneaked into the 15th-floor room and sealed the cave.

  I've been monitoring my surroundings, but right now, I can't monitor the real world outside the cave. And the cave disappeared while I was pulled into that illusion by the black jade, making it even harder to observe if anyone was outside.

  Plus, this reasoning has another despairing issue.

  Just like my initial worst-case assumption, opening and closing the cave can only be done from outside; it can't be opened from this side.

  Taken from Royal Road, this narrative should be reported if found on Amazon.

  I'm truly at a dead end.

  No, I haven't fought to the bitter end yet—surrendering like this would be too pathetic. If I'm yearning for adventures beyond reality, I shouldn't just sit here waiting to die. I need to struggle until my last breath; that's what fits my aesthetic.

  So, how should I struggle? My location and the ritual circle outside aren't even in the same spacetime... wait, Agent Kong mentioned before that this alternate space overlaps with real spacetime. If it's overlapping, I can't simply treat them as "not together."

  In other words, if I draw the letter patterns from the black shag rug on the ceiling, could they overlap with the ritual circle outside?

  There's still a problem: the ceiling surface and the floor surface aren't exactly on the same plane... but the patterns on the black shag rug aren't perfectly on the same plane as the ritual circle on the floor either. If it works over there, maybe I can try it here. Though the deviation is much greater on my side—how many centimeters thick is this floor slab, anyway...

  Screw it, thinking too much won't help; better to just try it!

  I raised my right hand, pointing my fingers at the spot on the ceiling where the cave entrance originally was. Flames suddenly burst into existence, slithering through the air like thin snakes, climbing up to the ceiling's surface.

  The letter patterns on the black shag rug spell out "rug," I remember that clearly. Then the font style and size... I recalled while adjusting the fire snakes' positions, finally shaping them to match my memory.

  After finishing the task, I let out a long breath and nervously watched the ceiling.

  Nothing changed.

  I couldn't help but feel deeply disappointed.

  So it doesn't work? Is it because we're not in the same spacetime, or because the floor is too thick, and the planes deviate too much?

  Or maybe because I shouldn't use flames to draw the patterns? The ritual circle was drawn with blood; perhaps I need blood too... but the letters on the black shag rug aren't blood either. Unless that filthy rug, as a murder scene item, has bloodstains soaked into it...

  I craned my neck to observe, moving around to view the flame letters I'd assembled from different angles. After all, maybe I spelled the word wrong.

  Walking around in this posture was making my head spin; soon I felt queasy, so I lowered my head, closed my eyes, and rested for two seconds.

  And when I reopened my eyes, something unbelievable happened.

  A concrete staircase had appeared in front of me out of nowhere.

  After a stunned moment, my gaze followed the staircase upward, and at its end on the ceiling, there was a light brown wooden lid.

  The cave's entrance had reappeared!

  -

  Why the entrance didn't appear immediately after I drew the letter patterns with flames—I only came up with a half-baked theory about that afterward.

  This theory is kind of ridiculous: at first, I was standing right under the cave, and the concrete staircase later appeared in that exact spot. Like in a strategy game where new buildings can't overlap with existing ones, maybe the staircase and entrance couldn't show up right away because I was occupying the space.

  To avoid any more mishaps, as soon as I spotted the entrance, I sprang into action, climbing the staircase to the wooden lid, then pushing it open directly and returning to the 15th-floor room's floor.

  I was finally back in the real world.

  I looked around and let out a long sigh of relief.

  At the same time, I vaguely felt that the near-enlightened mindset I'd had down in the cave, facing solitude and death, was slowly ebbing away.

  That enlightened state must be something that only emerges in special circumstances—something I couldn't hold onto after surviving. But I think it left a special mark on my heart.

  The me now is completely different from the me who hadn't entered the cave.

  I mulled over my reflections, then turned to look behind me.

  Let's set aside the philosophical stuff for now and deal with the practical issues.

  When I pushed open the wooden lid, I didn't feel the black shag rug that should have been covering it. And after emerging, I saw the rug still piled off to the side as before. That means during my time in the cave below, no "unidentified person" had entered the 15th-floor room to cover it with the rug.

  Since my method got me out successfully, my reasoning about the cave's appearance and disappearance pattern is correct. But if there was no "unidentified person," how do I explain why the cave's entrance disappeared before?

  I racked my brain but couldn't figure it out, then turned back to look at the cave entrance.

  This cave, this basement... I thought I'd figured it out, but there are still so many unknowns.

  For one thing, I still don't know what that black jade I got from the basement really is, or what those misty illusions and three shadows were about.

  There are still secrets hidden below that I don't know.

  Maybe... I should go down one more time?

  It might seem unwise to turn back right after barely escaping with my life, but this cave will be destroyed tomorrow. If I don't finish exploring now, I probably won't get another chance.

  I genuinely considered it, but then another anomaly made me shelve the plan for now.

  All the "fireflies" I'd set up in the real world had vanished. Needless to say, that's because I'd lost connection with them while in the basement. The biggest problem is that now I've lost monitoring on Alice.

  I couldn't stay put anymore.

  Alice keeps talking about leaving me from time to time. If it was just a short loss of monitoring, I could accept it—rush there and back, that was my initial thought. But now that it's been a long time without monitoring her, the situation changes. If she really leaves during this window, I'll never find her again.

  It's probably Alice's jinx-like aura that let me encounter these weird events, and I'm not dumb enough to confuse a single feast with endless meals.

  I also can't explore the basement while sending out "fireflies" to head home, so I have to drop this for now.

  But before leaving, I still took photos and videos of the ritual circle and the black shag rug from different angles. Maybe someday I can replicate this circle elsewhere.

  After doing all that, I turned and left the 15th-floor room, walking all the way out of the apartment building.

  Looking at the moon in the night sky, I finally felt that sense of "seeing the light of day again."

  But I hadn't gone far when, ahead in my field of vision, a bizarre, distorted shadow emerged in an eerie way, blocking my path.