The next day, just as before, Hayasaka Tooru—Tooru—turned on his body camera, confirmed that the stream had begun, and started his “cleaning” of the Sugai Dungeon.

As might be expected, his report about the strange noise appeared to have been completely ignored. There were no signs of an investigation, and it did not even seem as though anyone had checked the stream in the first place.

That said, Tooru himself had forgotten to review the stream and confirm the exact point where the noise could be heard, so he did not feel particularly inclined to blame them too harshly.

“Rats, four.” “Furballs, three.” “Demi-gob, one.” “Furballs, two.”

As usual, he methodically beat the trash mobs to death, gathered up the rice-sized magic cores, descended one floor to the second, continued cleaning in the same manner, and then moved on from the second floor to the third.

And from there, he went straight to the spot in question.

“…I can hear it after all.”

A keeen—a high-pitched sound like a mosquito whine or tinnitus. Tooru clicked his tongue at his own carelessness for not checking whether the microphone had picked it up, then stood still for a short while, just as he had the day before.

An idol explorer his own age was challenging a B-rank dungeon somewhere, while he himself was being troubled by an incomprehensible phenomenon in a D-rank dungeon.

Well, whatever—he thought, half in resignation, and took a step forward.

At that moment—

There was a human figure at the far end of the corridor.

“…You’ve got to be kidding.”

He muttered under his breath and narrowed his eyes. There was no mistake—a human silhouette stood there. At a distance of about thirty meters, right at the limit of what the dungeon’s glow allowed him to see, was a man wearing hakama.

Reflexively, Tooru pulled his terminal from his pocket and checked the stream time.

“Three hours fourteen minutes. I found a human silhouette at the location of the strange noise. I don’t know if it’s a human or a humanoid monster. If it’s a monster, it shouldn’t be in the upper layers of the Sugai Dungeon. There’s a possibility of a dungeon stampede, or some unknown anomaly… maybe. I don’t know.”

For the time being, he simply voiced his thoughts into the microphone as they came to him.

Was the camera even capturing the figure?

The silhouette remained where it was, still at the thirty-meter mark. Tooru checked the stream display, but on the small screen of his terminal, it was hard to tell. It looked like something might be there—but it could just as easily have been his imagination.

Then, suddenly, the figure moved.

It was a motion that seemed to beckon him—come this way, as if inviting him to follow.

“…Just… check it. I’ll just check, then run.”

Rationally, Tooru knew exactly what a cleaner should do when faced with this kind of situation: if something strange happened in a labyrinth, the proper response was immediate withdrawal.

Yet, he could not resist the inexplicable urge gnawing at him, a kind of restless anxiety, and found his feet moving in the direction the man in hakama had vanished toward.

The figure continued deeper and deeper into the labyrinth.

Tooru followed—not running. For some reason, the man seemed to pause and look back as if waiting for him to keep up, confirming that he was indeed following.

“Damn it… this is definitely a bad idea. If something happens, it’s going to be my responsibility…”

He knew what he was supposed to do: encounter an anomaly, retreat immediately, and report it.

He also knew that if he didn’t, no one would cover for him. It was clearly written in the cleaning contract he had signed.

But—no one was going to guarantee his life for him.

“Yeah… if something happens, it’s my responsibility. But I reported it at the Sugai Dungeon branch yesterday. They ignored it, didn’t even pretend to investigate. Maybe I can shift a little responsibility onto the office too…”

Muttering to himself, he continued after the figure in hakama.

They moved for a while, turning right, then left—Tooru mentally cross-referenced the familiar map of the third floor, but he couldn’t determine their destination. They weren’t heading toward the stairs to the fourth floor, nor back down to the second.

It started to feel like he was being toyed with.

Then, abruptly, the figure slipped into a wall.

“…What?”

He had been moving along a straight corridor, then the figure turned left… and went straight into the wall. Tooru saw it happen clearly, disbelief sparking dozens of question marks in his mind, yet he arrived at the same spot where the figure had disappeared and reached out and touched the wall.

No—he couldn’t touch it.

His hand sank into the wall.

No—that wasn’t right either.

What had appeared to be a wall was actually a passable space.

A hidden passage, disguised by holograms, spatial visions, or—if one wanted to think magically—simply an “illusion.”

“Come one, now… seriously?”

The Sugai Dungeon had been fully explored two years before Tooru took on the cleaning job—five years ago from now.

Since then, few explorers had entered, and before the city started recruiting cleaners, city officials apparently did some cleaning three times a year—but he had never heard of a hidden passage like this.

In fact, with no hints at all, it would have been impossible to discover. No one would ever bother combing the shallow layers of a D-rank dungeon, and even Tooru, after three years of walking these floors, had never noticed it.

Beyond the wall lay a simple small room.

At most the size of eight tatami mats, it seemed surprisingly cramped for a dungeon chamber—but Tooru didn’t know much about other dungeons, so maybe such rooms weren’t uncommon.

On the far wall, something like a painting was displayed.

A painting on a dungeon wall…?

Curious, he stepped forward—but there was no floor to step on.

The “floor” had been an illusion. He passed right through it—and fell.

◇◇◇

When an object begins free fall, it supposedly drops over seven meters in just a little more than a second.

That’s ignoring air resistance, of course, but in Tooru’s perception, it felt like he fell for over ten seconds, maybe less than thirty.

Ah… I’m dead.

That was his honest thought.

B-rank or higher explorers apparently take almost no damage from the impact of free fall. Of course, that assumes a proper landing—but even so, it’s a testament to how abnormal explorers are. Some C-rank explorers might counteract the impact with magic or abilities, and a few could manage it with sheer physical prowess alone.

Tooru was below D-rank.

Not even an explorer—just a cleaner.

He was almost certain he was going to die. And if so, he figured he might as well curse his luck or mutter some snide remark—but unfortunately, nothing witty came to mind in that split second. He barely had the luxury of thinking while falling.

The crash—the impact—was… smaller than he expected.

It felt more like falling off a half-meter ledge. Perhaps because he’d curled his body instinctively, he hadn’t landed on his head—thankfully—but his back took a heavy blow.

“Kah—!”

The air was forcibly expelled from his lungs.

But that was it.

Tooru reflexively sat up and checked himself for injuries. Legs, arms, back, neck… no fractures. His back was sore from the blow, but nothing fatal.

“Why… am I ali—”

He was about to finish that thought when a sharp sense of danger made him spin around.

The scene hadn’t changed much: the Sugai Dungeon corridor, its familiar walls faintly glowing, the textured stone-like labyrinth structure.

He had fallen right in the middle of a straight passage, stretching at least sixty meters in either direction with no end in sight.

And at the far end of that straight path… there was a black Oni.

An ogre. A humanoid monster, at least C-rank level, all muscles and menace. Horns sprouted from its head like the Oni in old tales, and the sheer killing intent radiating from its body made the air itself feel tense. Even the dumbest person could recognize it as a threat.

Its eyes gleamed like a wild animal in the dark, and it was watching Tooru.

“…!”

Without thinking, Tooru grabbed his trusty iron-rebar club from the floor and bolted in the opposite direction from the ogre.

As he ran, a snippet of trivia popped into his mind: never turn your back on a wild bear… too late, of course.

The delay between Tooru taking off and the black ogre starting to chase him was maybe two seconds. The time it took for the ogre to close the gap? Not even a second.

In an instant, the black oni was on his tail.

Every strike from that ogre would be fatal to Tooru—probably even a flick to the forehead would smash his skull.

“—Kuhh!”

The iron-rebar club in his hands was released more than thrown. Running at full speed, he couldn’t manage a proper swing.

And of course, it was almost useless.

The ogre swatted his makeshift weapon aside like an annoying insect, and in the next instant, Tooru himself was hurled forward—over twenty meters along the straight corridor in the direction he was running.

It might have felt to the ogre as if it had merely nudged him, but that nudge sent an adult man flying, crashing him into the floor, rolling him along, and somehow using that momentum to spring back to his feet.

Pain? He didn’t even register it. For the moment, he was alive.

Probably not for long. Almost certainly, he was going to die. And yet… he was still running.

“…!”

The straight corridor stretched endlessly. He couldn’t see the end. His body felt like it was moving through a dream, slow and sluggish. Maybe time was stretching as he neared death, instead of seeing a flash of memories, he thought, half detached.

Another breath—or maybe two—and the black ogre’s arm would punch straight through his back. That would be it. His skull could be shattered, his body slammed into the floor.

In that extended moment, Tooru’s eyes caught sight of the man in hakama.

Just five meters away.

Even on a straight corridor, the man casually turned right and disappeared into the wall again—another “illusory wall.”

Tooru executed a forward roll, throwing himself across the floor with all his strength.

Instinct. The ogre would strike any moment. He had no chance afterward, so he had to at least dodge one attack.

Miraculously, the timing aligned. The black ogre leapt over Tooru’s rolling body, clearing him entirely.

“Haaah—!”

He took one shallow breath. With no time to savor the miracle and not even a moment to stand, Tooru crawled across the floor like an insect and slipped into the illusory wall.

He emerged into a room.

This time it was not a small chamber. It was about twenty square meters—too small to be called a large hall, but clearly larger than before. It had a floor, walls, and a ceiling, and nothing else—no, there was something.

Two blades were embedded upright in the center of the room.

One was a Western sword. Both blade and hilt were long, giving it a sleek silhouette.

A double-edged sword of the hand-and-a-half type.

The other was a katana.

A bare blade stained a dark, reddish black, with a black guard and hilt. The blade itself looked to be about seventy centimeters long.

They were practically side by side.

The distance between the sword and the katana was less than a meter.

At that moment, Tooru reached for both of them without thinking. Why such weapons were lined up and thrust into the floor in a place like this—how the katana radiated an ominous, cursed-looking air at a glance—or how the Western sword somehow felt strangely sacred—none of that crossed his mind.

He was about to die.

There were weapons right in front of him.

That left only one choice: to struggle uselessly to the end.

The sword in his right hand.

The katana in his left.

He grasped them, pulled them from the floor—and his consciousness went dark.