“Meaning tall, well-sealed buildings like this might have lower densities?”

  “I think that’s a reasonable assumption.”

  It was true that when I had used Life Detection back at Shinjuku Gyoen, it felt like I had been able to search in a wider area. Maybe that meant that areas with D-Factor densities beneath a certain threshold effectively became unsearchable. Although admittedly, undead creatures barely showed up on Life Detection to begin with, and certain monsters like lesser salamandoras and chamimiclons could avoid detection completely, so there might be multiple factors to consider.

  “It’s a really interesting theory, but we’ll have to think about it later. Our first priority—”

  “—is making sure Komugi is safe and sound,” Miyoshi said, finishing my thought.

  “Since there actually is a faint signal, if it’s her, that means she’s alive.”

  “The fact that it’s faint makes it sound like she might not be for much longer, though,” Miyoshi countered, grimacing.

  “I really hope you didn’t just speak that into existence...”

  Keeping an eye on our surroundings, I ran as fast as I could toward the apparent source of the signal.

  ***

  “Is this the place?”

  “I think so.”

  The signal that I had picked up on Life Detection was behind the door in front of us. There was a sign above the door with “Appraisal Room 2” written on it.

  I swiped my key card in front of the reader at the entrance, and the door immediately unlocked with a soft beep. Gently opening the door a crack, I cautiously called out our missing acquaintance’s name. We had no way of telling whether it was her inside the room, after all.

  “Rokujo?”

  Flinging open the door, Miyoshi ran swiftly past me, dodged around the desk, and headed over to the corner of the room where the signal seemed to be coming from. There, she was greeted with a concerning sight.

  “Rokujo?!”

  A pair of legs were sticking out from under a blanket.

  I immediately rushed over, yanked the blanket away, and checked her neck for a pulse.

  “Looks like she’s just unconscious.”

  “I’ve got some ammonia,” Miyoshi offered.

  She really does have something for everything, I thought to myself with a chuckle as I lifted Rokujo’s torso and placed the ammonia under her nose.

  HURRY

  “In here?”

  “That’s right. Then it sounded like something fell, and when I came up for a closer look, I saw blood...”

  When she came to, we confirmed that Rokujo was unhurt. After she had seen something that appeared to be blood while we were on the phone, she had heard some kind of loud sound and then fainted. Is someone who’s that much of a scaredy-cat really cut out to be a dungeon explorer?

  At any rate, she was fine. Relieved, I was ready to leave the building right away, but Miyoshi suggested that we might as well give the place a quick sweep, just in case.

  “So, blood, you say?”

  Miyoshi shone her flashlight over the area where it had supposedly been, but we didn’t see anything that looked like bloodstains. I even ran my fingers along the opening of the bottom drawer, but didn’t end up with anything sticky on them.

  “No sign of blood that we can see.” Miyoshi murmured. “Hmm...? The drawer’s locked.”

  “Oh, just a moment!”

  Rokujo pulled a key out of her purse and handed it to Miyoshi, who opened the bottom drawer of the desk and immediately pointed her flightlight inside.

  “Hmm, nothing really stands out— Huh?”

  “What is it?”

  “Ummm... There’s a hole in the bottom. Has it always been like that?”

  Miyoshi stuck her hand through the hole and then out around the side of the open drawer, closing and opening her fist a few times. Apparently it was a pretty big opening.

  Rokujo merely shook her head, stunned.

  Putting my hand inside the drawer, I felt around for the bottom of the drawer just above it and found exactly what I expected to find.

  “The next drawer up has a hole in it too.”

  “What?”

  We unlocked all of the drawers and inspected them. Every single one had a roughly circular hole in it, as if something had melted all the way through from the top to the bottom.

  “What is going on?”

  “It’s like someone was keeping a xenomorph locked in the top drawer, and it deliberately injured itself so it could escape,” I said.

  “If that were the case, Komugi’s hand would’ve gotten messed up pretty badly when she touched it. You did touch that bloodlike stuff, right?” Miyoshi asked.

  “I sure did.”

  But there was no bloodlike stuff to be seen.

  I got down on my stomach to take a look under the desk, then reached my hand in.

  “Kei, you probably shouldn’t just shove your hand into random holes. You might end up losing it.”

  “No, there’s something under here...”

  I had stuck my hand in because I had seen what looked like a darker area, and sure enough...

  “It’s a hole.”

  “Another one?”

  Once I had stood back up, Miyoshi and I lifted the hole-riddled desk and moved it to the side. Underneath it, there was a gaping hole in the floor about thirty centimeters wide—positioned directly beneath where the hole in the bottom drawer would have been when it was closed.

  “It looks like this is a raised floor, and there’s an open space underneath it,” Miyoshi observed.

  “What could’ve even made a hole like this, anyway— Hmm?”

  Noticing something that had apparently fallen out of one of the drawers into the floor hole, I picked the object up.

  “Is this...”

  It looked like a fragment of something I had seen before.

  “That’s a piece of one of the potion cases you made, Kei!”

  “Ah!”

  Rokujo had apparently put the adventuring kit we had given her in the bottom desk drawer. The set had included a first-rank potion.

  Miyoshi eyed the fragment.

  “I’m not sure whether to call this broken or melted...”

  It was almost as if the middle portion of the cylindrical case had been melted away, causing it to break apart afterward.

  “Either way, the potion is probably a goner as well,” I said.

  “Maybe that is what Komugi found?”

  Potions were red in color; if she had gotten some on her fingers, she could have mistaken it for blood in the dark. Of course, a potion was a lot less viscous than blood, and there wouldn’t have been very much of it. But unlike blood, potion contents just vanished into thin air once they’d taken effect, which could explain why there was no trace of it left now.

  The question was, did that mean something wanted the potion and went under the floorboards after it?

  Miyoshi pointed her flashlight into the hole in the floor to see how things looked. Inside, several cables had melted, and portions of them appeared to be charred, leaving the faint smell of burnt electronics hanging in the air.

  “I suppose the short here must’ve tripped the breaker, then?” she surmised.

  “Maybe. How far down does the damage go, anyway?”

  She shone the light further down. There, we saw that one portion of the concrete slab was bare, unlike the rest of it.

  “It looks like there’s maybe a twelve centimeter hole gouged out of the concrete.”

  The area Miyoshi was pointing to was a clean cut through the slab, like a giant scoop taken out of a bulk two-liter ice cream container. Cross sections of rebar gleamed in the flashlight’s beam.

  I raised an eyebrow.

  “Did this thing just take a chunk right out of the floor, reinforced steel and all?”

  “The cuts are so smooth, it’s like something just melted through it and carried it away,” Miyoshi murmured in awe, then reached in and traced a finger across the border of the concrete and metal. “Super smooth cuts.” When she finished her inspection, she stood back up and quipped, “It’s like someone from Marukami Village with a jewel in their forehead stopped by.”

  “What is going on here?”

  If it could do something like that, whatever this thing was could probably whittle its way through anything in the entire building.

  What if the next place it cuts through happens to be something important for maintaining structural integrity? What if it causes the building to no longer be able to support its own weight?

  It wasn’t hard to imagine that turning into an absolute disaster.

  “First of all, where did our, um, culprit, even go?” Miyoshi wondered out loud.

  The raised floor inside that room was only maybe twelve or so centimeters high. If whatever it was escaped by crawling under the floorboards, it had to be that size or smaller—at least in height.

  Suddenly, a desk on the other side of the room tilted downward, making a loud sound.

  Rokujo let out a shriek.

  “Miyoshi!” I shouted.

  Just then, out of nowhere, a signal appeared on my Life Detection.

  “There’s something under the floor!”

  The signal was there briefly, but by the time we made it over to the desk to check underneath, it had vanished into thin air.

  “What the hell is going on?!”

  “It looks like one of the supports for the raised floor disappeared, and the floor buckled under the weight of the desk,” Miyoshi explained.

  “Can we send in the Arthurs?”

  “If they pop out of the shadows while they’re under there, we’ll have an even bigger mess on our hands up here.”

  They might’ve been able to chase after it while hiding in the shadows, but they had to come out to affect anything in our world. Even Glas or Gleisad wouldn’t have been able to fit inside that narrow of a space.

  “Any chance we can drop it into a good ol’ shadow pit?” I asked.

  “We don’t even know what we’re dealing with, much less how big it actually is...”

  Whatever it was, it could easily cut through a concrete floor slab. We definitely had no idea what might happen if we tried to dunk it into oblivion—without a clear idea of its size, we could end up causing a huge impact to the surrounding area.

  “I guess we’ll have to save that for a last resort,” I mused. “But why did it suddenly show up on Life Detection for a bit?”

  “If our hypothesis about Life Detection from earlier was accurate, then maybe there was a sudden increase in D-Factor density in that area?”

  “Maybe it came out of hiding to reveal its location to us?”

  “What would be the point of that, though?”

  “Fair enough... I guess if we just consider the phenomenon itself, it would make more sense to assume that the D-Factor density in the area increases when it cuts something away.”

  Miyoshi blinked.

  “Would that mean that when it cuts things away, it releases D-Factors?”

  “Maybe.” It was possible that it used the D-Factors in the process of breaking down matter.

  “Anyway, we may not know where it came from originally, but if we think about the series of events so far, it must have started out in the top drawer of Komugi’s desk. From there, for some reason it deliberately melted through the floors of multiple drawers until it reached the bottom one, then proceeded further down to the floor.” Miyoshi pointed to each drawer in order as she spoke, ending at the hole in the floor. “Almost as if it were chasing after something.”

  Hearing that, Rokujo finally spoke up in a quiet voice.

  “The top drawer...?”

  Suddenly, an idea came to me.

  “Was it after the potion?”

  Based on Rokujo’s testimony, the contents of the potion had definitely leaked out onto the floor. If the culprit had dissolved the bottoms of the drawers in search of that, then further dissolved the raised floor and even part of the slab beneath it, where some of the liquid might have fallen down to...

  “You know, I wonder if we could lure it out with another one?”

  I made a show of reaching into my pocket and ostensibly produced a first-rank potion from within, though as per usual, it really came out of Vault.

  “Possibly,” Miyoshi said, eyeing me. “That’s a million-yen piece of bait you’re using, though.”

  Just then, Rokujo sheepishly interrupted our conversation.

  “Um, excuse me...”

  “Is something wrong?” Miyoshi asked.

  “I’m, uh, pretty sure it’s a slime doing all this.”

  “A slime?!” Miyoshi and I shouted in unison.

  Rokujo went on to confess to us how, entranced by its beauty, she had ended up smuggling a slime core out of the dungeon and adding it to her collection.

  I was almost at a loss for words.

  “Can slime cores even regenerate outside a dungeon?”

  “What if there were some magic crystals nearby?” Rokujo asked.

  “Magic crystals? In a GIJ office?”

  As we scratched our heads, confused, Rokujo started explaining the incident to us from the very beginning.

  “So here’s what happened—”

  Apparently, it had all started with various dungeon-produced stones disappearing from around her desk.

  “I guess stones from the dungeon have D-Factors in them?” I wondered.

  “Probably,” Miyoshi replied.

  “So presumably it used those to regenerate its body.”

  “I doubt the other stones provide D-Factors in quantities nearly as large as magic crystals do, though.”

  I rubbed my chin.

  “So while it was desperately attempting to regenerate, there just so happened to be a first-rank potion in the same desk.”

  I figured potions were chock-full of D-Factors. Absorbing one would probably have brought it back into tip-top shape or even better...

  Suddenly, another loud crash reverberated from across the empty room. Apparently several desks a short distance away had fallen into the floor.

  “Uh, is it just me, or is it caving in wider areas than it was before?”

  “Maybe it’s still growing?” Miyoshi suggested.

  “At this rate of growth, we’re gonna be in big trouble—”

  I barely had time to finish my thought before a powerful signal appeared underneath us and started moving, sending desk after desk crashing through the bottom of the floor in its wake.

  “Eeeeek!!!”

  “What’s with the horror movie schtick?!”

  Once the entire row of desks by the window had fallen down, the signal disappeared again, and the room fell silent. The only sound we could hear drifting across the room was Rokujo breathing heavily.

  “It can actually break things down while moving at that speed?” Miyoshi murmured incredulously.

  It certainly seemed like an entirely different beast from the slimes on the first floor of Yoyogi.

  “This thing was left in an environment with an extremely low density of D-Factors, and still managed to regenerate.”

  “The little guy’s got spunk,” Miyoshi admitted.

  “I wouldn’t be surprised if it even adapted to its environment somehow during that whole process.”

  “Hey, do you think it’s possible for slimes to even have spunk?”

  “How the hell would I know?”

  There were lots and lots of slimes inside the dungeons. Whenever someone brought in an object from the outside, it was as if they all came out of the woodwork at once. But there was only one single slime in the building we were in.

  With so many objects around it that needed to be broken down, was it even possible for one slime to do that on its own? What if, through some kind of instinct, it acquired the power to make that possible when it regenerated from its core in a location mostly devoid of D-Factors?

  “Wh-Why isn’t it breaking everything down at once?” Rokujo asked, looking around the room that had quieted down again. All the desks by the window were in rough shape, with most of their legs having sunk into the floor.

  “Maybe it’s taking a postmeal nap?”

  The reason it only shows up on Life Detection when it’s breaking things down is probably because that’s when the D-Factors are doing their job. Then it would make sense to assume that the reason it disappears instantly afterward is that as soon as it finishes absorbing everything, it assimilates into its environment. It’s like a form of camouflage.

  After that, it probably uses whatever it broke down to reconstruct itself. One might even say it’s evolving to adapt to its environment—though it might be too sudden a change for that to be an accurate description.

  “It’s called ‘expanded reproduction,’ right?” Miyoshi said.

  “With an extremely high rate of accumulation,” I added.

  At any rate, we can’t afford to let it out of this room. We don’t know exactly how much of the blame can even be placed on Rokujo—and never in my worst nightmares would I want to see a massive monster that can swallow entire buildings show up in the middle of Tokyo and face off against the JSDF.

  “Anyway, we need to do something about this before it turns into a kaiju movie,” I muttered.

  “Well, we’re only up against one slime. We have a guaranteed method of taking it down in one shot.”

  I squinted in thought.

  “Hmmmmm...”

  “What’s wrong?”

  “You don’t think pieces of it would just start falling off before the surfactant could spread across its entire surface, do you?” That wasn’t an issue with ordinary little slimes, but would we really be able to destroy a giant one instantaneously?

  “I couldn’t tell you... We’re not even sure how the mechanism behind it works to begin with,” Miyoshi reminded me.

  “I really don’t even want to imagine facing off against a giant tentacle thing with our Benzetho-Blasts...” That’s the kind of thing you see all over the place in low-budget monster horror flicks.

  “We should probably just lure it out and finish it off before it makes another move.”

  I nodded.

  “Agreed.”

  May as well take this opportunity to have Rokujo hide out in the hallway. At this point, we’ve got no choice but to give up on this disaster scene of a room.