The mice going through the underground passage.

We entered the small building through the ventilation opening. The only thing on the inside was an incredibly weirdly placed staircase going down… like what, was the entire building just a front for the stairs?

Weapons hang on the walls, but there are no tables or chairs in sight. In the center, there's just an obviously conspicuous descending staircase… It's as if the cabin itself is nothing more than a disguise to hide the staircase.

"It could just be a basement… but this is too suspicious. Does it not even having handrails mean they usually cover it up?"

[Probably. But then it being open right now is strange.]

"It's convenient, but we should be cautious about traps."

"Oh? Can't we just ignore traps? That's what we're using mice for after all."

"… You're right. Let's go ahead."

As Rokuko said, it'd just be mice getting caught in the traps. We made sure to use only seven mice so as not to attract attention, but we could still send in replacements if needed. As a result, we lined the mice up and had them run towards down the stairs.

Past the staircase on the underground first floor was a white-walled corridor. One of a dungeon's features was that it wouldn't appear dark even without a light source.

"It's a dungeon… right? It's so well-maintained though."

"It really is. I can't say for sure unless we actually went there to see it though."

A dungeon in the Holy Kingdom, a country known to advocate for dungeon extermination, would be quite a scandal just by its existence, let alone being hidden in a cabin.

[Unless it is completely managed, yes?]

"If they're hiding it, they must feel guilty."

Otherwise, they wouldn't hide it in a cabin. They could just make it a tourist attraction and have it open as a practice dungeon.

… Would that shake the foundations of their dungeon extermination policy?

[We will continue to proceed further inside.]

"Go for it… How far does this corridor go?"

"Rokufa, could you open the map for us as well?"

[Yes, of course.]

Dungeons were excellent for making underground passages. There was little risk of collapse even if it ran just below the ground. It could even be repaired quickly if ever broken.

Looking at the map Rokufa opened, it was heading towards the center of Kuromaku.

"… It's definitely heading to the center, but is there anything there? I can't tell from the map."

[Excuse me, Kehma-sama. Allow me to answer that for you… It's the Church of Holy Light's Church District.]

Toy interjected with a smile.

In the town of Kuromaku, a special place without any buildings covered in black cloth. A religious district.

[If we proceed according to this map, it seems we'll go further toward the center, under the church headquarters—oh, it looks like there's a fork in the road. What should we do?]

We stopped for a moment and confirmed that there was a side path at a right angle to the path heading straight forward.

The side path was separated by a gate that looked like the entrance of a prison cell. It looked like humans wouldn't be able to pass through without a key, but it was rather convenient for the mice as they could just slip through.

"Let's split into two groups. Hamelin 5 and beyond will go straight. The rest will take the side path."

[As you command. Rokufa, please take care of Hamelin 5 and beyond.]

[Yes, understood.]

I decided to send three of the seven mice straight ahead and have the rest explore the side path.

… Both that path and the one shown on the monitor had white walls and stone-paved floors.

"It's well maintained to not fall into disrepair. If this is a dungeon, someone in the Holy Kingdom must be a Dungeon Master!"

"That's right. If it's managed, that must be the case."

Although Haku-san was called a traitor, whoever was siding with the Holy Kingdom had to be a traitor as well.

"Kehma, there's something here."

"Oh, it's a room."

There was a small room without a dungeon-like door. Peeking inside, I saw a black Dungeon Core.

"Uwahhh, what's that thing? It's so gross."

Rokuko expressed her discomfort.

Dungeon Cores were normally white, glowing spheres the size of a basketball. However, this Dungeon Core is black and had numerous cable-like objects connected to it. They were connected to the ceiling, walls, and a stone slab in front of it. The stone slab didn't have anything carved on it, but… what is it?

"Rokuko, is this a Dungeon Core?"

"Well, it seems to be, but… it's really disgusting. What is it?"

She seemed to feel a strong sense of discomfort and disgust from the image on the monitor, to the point that she couldn't confidently say that it was a Dungeon Core.

"Even so, why is the core located in such an ordinary passage… and for it to be the very first place we found… What does this mean? Is it a Dummy Core?"

"Umm, I can't explain it well, but it doesn't seem to be like that."

If a Dungeon Core said it was different, she was probably right? But for a main core to be in such a place near the entrance without any obstacles? Something seems off.

[Master. Hamelin 5 and beyond have arrived at the opposite side of the passage. It seems to be a basement. There are stairs going up.]

It seemed that Rokufa had proceeded underground and arrived at the basement of the church. Looking at the map, it was indeed the basement of a church. Is it connected to the outside of the district through an underground passage? Is it an evacuation route or something?

"For now, mark it on the map. It would be nice to confirm it from above ground as well, but would it be difficult to enter the church? It would be fine if ordinary people could enter."

[Understood. It seems to be a dead-end here. There are doors, so we can't proceed further.]

Beyond the basement's stairs of the church, there were iron-barred doors and regular wooden doors. Mice couldn't open wooden doors.

"Leave Hamelin 7 behind and have the rest join us. If someone opens that door, have 7 go through it. Until then, let it lay low."

[Yes, understood, Master.]

I instructed Rokufa to have the two mice join us. Currently, there was only one straight passage with a side path and a single room, but the map was filling up smoothly. Let's continue investigating this mysterious dungeon.