and headed for the tunnel, but soon ran into an obstacle. It was a cave-in.

Something is wrong. This area is supposed to be a well-reinforced section.

Yes, it is. That means it must have been artificially collapsed.

Should we try to get to the other side somehow?

I think that's a good idea.

So and remove the collapsed rocks.

As expected, the tunnel itself was strong enough that it did not collapse as soon as the rocks were removed, and after 20 minutes, a hole was made in the tunnel that was strong enough to pass through.

Okay, let's go.

Let's go.

The two bodies then proceeded to the end of the tunnel.

[...... hydrogen sulfide]

Mm-hmm.

The smell of hydrogen sulfide wafts from the depths of the tunnel. It seems to be quite concentrated.

The two bodies wonder if this might also be a legacy of this .

* * * *

>

"I see, so that's how it goes."

In the cafeteria of the laboratory in Horai Island, the old man was reporting to Jin and the others about the results of the investigation of <> and <>.

Presently present in the cafeteria are Jin, Erza, Hanna, Saki, Goose, Marikka, <> Turles, Neige, Rouge, and others.

"If we could monitor the vision and hearing of those <> and <>, we could get more information in real time."

"Brother Jin, you should have told us that when we decided which golem to dispatch."

"Erza-chan is right, Onii-chan."

Jin blurted out, but Erza and Hannah caught him in the act.

<

"Oh, that's a good idea. I'd appreciate it."

If this were a human, we would be able to know what they are talking about with <>, but against a golem, it would be useless.

Therefore, we are forced to stare at a silent screen, just like in a silent movie.

However, the old man, who has assessed the situation, explains the situation as appropriate, which is a great help to us.

"Yes. Is there hydrogen sulfide ahead?"

This information is obtained from < through Jin D. and Marikka D.

"Kuhu, you said that <> is specialized in production, right?　If so, what can we extract from the mine?"

"Metals and magical crystals for sure."

"Yes, just as Jin predicted. The problem is the rare ores.

Saki was hoping that rare minerals would be produced.

However, his expectations were betrayed in many ways.

* * * * * * * * * * *

The tunnel is heading steeply into the ground. The concentration of hydrogen sulfide is increasing.

There is no sign of destruction in this area.

Hmm. But we can never be too careful.

I know.

The reinforcement of the ...... tunnels has begun to corrode, albeit slightly.

Hydrogen sulfide.

Hydrogen sulfide corrodes silver, copper, and many other metals. This is mainly due to the action of sulfur.

It is a combustible gas and produces sulfurous acid gas when it burns. It is also toxic.

But I don't understand. If the purpose is to corrode, there must be something more powerful.

That's for sure. We'll have to investigate that as well. ......?

We have reached a fork in the tunnel.

It is a small, wide hall-like space where the tunnel divides into five different directions, except for the one we came from.

What should we do?

There is no sign of the enemy at the moment. Then it doesn't matter which way you choose.

Then we should go first to the right.

That's fine.

After a brief exchange of words, <> and <> entered the tunnel on the right.

The tunnel was nearly horizontal, and the smell of hydrogen sulfide had diminished.

The tunnel seemed to yield quartz and quartz-like minerals.

Hmm, a tunnel of magical crystals.

Yes, it seems so.

The tunnel dead-ends after about 500 meters.

It looks as if there is nothing wrong with the tunnel, but in fact the situation is quite extraordinary.

There is not a single miner golem. That's not right.

I agree.

From the looks of it, the deposit is excellent, and it still seems to be able to mine magi crystals, but there is no miner golem.

Once again, the mystery has increased.

and return the way they came to the tunnel branch and step into the tunnel to the left this time.

This tunnel, too, is nearly horizontal and was dug in the same vein of magecrystal as the previous one.

And here, too, the situation was unusual in that there was not a single miner golem.

They turned around twice and this time chose the middle tunnel out of five.

It was a gradual descent.

The tunnel was a gentle descent. And the smell of hydrogen sulfide is getting stronger.

Pyrite is a bright gold mineral that crystallizes in cubes.

The golden dice specimens are well-known.

Its composition is sulfur and iron, with the chemical formula FeS2.

Its main use is in the manufacture of sulfuric acid.

It is rarely used as a steel material because the sulfur it contains adversely affects the properties of iron.

However, sulfide minerals are produced as ores of various metals other than iron.

Is this ...... a mercury deposit?

It would seem so.

Mercury sulfide is a red mineral called cinnabar.

In ancient times, it was called Niu, a red and vermilion pigment.

It is assumed that the name Niu means the place where Ni is produced, i.e., where cinnabar mines were located.

A word of caution.

Mercury is the only liquid metal at room temperature.

Mercury is toxic and is believed to cause brain and liver damage.

Could it be that they wanted mercury to disperse as a poison?

That's possible, but the tunnels are too quiet.

Mm. ...... indeed.

And this tunnel, too, was devoid of a single miner golem.

* * * *

Now here.

The fourth time we went to investigate.

This time, we surveyed the fourth tunnel from the right, i.e., the second tunnel from the left.

The tunnel extends underground at a steep angle.

There is no miner golem here either.

Hmm.

What happened to the miner golem is also a mystery.

At the moment, the number of mysteries increases with each investigation.

Even so, and cannot stop their investigations.

...... seems to be a deposit of silver mithril here.

Mm-hmm. There is also a small amount of gold.

and <> go on ahead.

And no miner golems here either.

I have no idea.

I agree.

and head for their fifth exploration, to the leftmost tunnel.