Horaijima, August 10.

The sky is blue and the breeze from the sea is cool in the morning.

Good morning, Elsa.

"Good morning, Brother Jin."

<

After washing their faces with cold water, they wake up refreshed.

"Here are your towels, father.

"Oh, thank you."

After receiving the towel from Reiko and wiping his face and hands, Jin spoke to Elsa, who was also returning the towel to Edgar.

"So, it's finally tomorrow, huh?"

"......."

With this conversation, the two men and the two bodies left the house and went to the cafeteria of the institute.

"Good morning, master."

"Good morning."

There, Peridot 1 has just finished preparing breakfast.

Of course, he knew that Jin had woken up and washed his face, so he calculated the time to come over here and prepare for breakfast.

Jin-kun, good morning.

"Hi, good morning."

Vivian and Saki had arrived too.

Some members of the Jin family had already arrived at Horai Island for the wedding ceremony scheduled for tomorrow.

Mr. and Mrs. Reinhardt, Count and Countess Kuzma, and Licia would be coming tonight because of their political duties.

Good morning.

Good morning, Jin.

Besides Vivian and Saki, Marcia, Rodrigo, Goose, Tor and his wife Stearina are here.

Meine is originally here and is taking care of Erza.

The old man also reports.

Jin listened to the report while eating breakfast.

"Thank you for the breakfast.

As Jin finished eating and drinking hojicha (Japanese green tea), Saki and Vivian seemed to have finished eating too.

And Erza seemed to have finished eating, too.

"So, Jin, what are you going to do today?

Saki came over to Jin and Erza's table holding a cup of tea.

"I've already prepared everything for you. ......

All we have to do now is to pick up Milowina, Jin answered.

"I see. I was hoping to hear more about that .

"Oh, I'd like to hear about it too.

Stearina came in with a cup of tea.

Jin-kun, I want to know too!

Toa, who had not yet finished eating, shouted from across the table.

Jin replied with a wry smile.

"Then let's spend the morning talking about it."

* * *

"Well, let's get started."

In Jin's workshop, most of the members of the who are currently on Horai Island are present.

The exceptions are Elsa, who already knows about , and her mother Meene. The two seem to be having some kind of conversation with the mother and son before the ceremony tomorrow.

"First of all, I think today's topic should be <>, right?"

No one objects. On the contrary, everyone looks as if they can't wait to hear what the topic is.

"Well then. ...... First, <> was mercury. Is this correct?

Everyone nodded silently.

"Mercury's <>, that's what <> is. In other words, it is not just mercury, but magical mercury.

Jin explains that it is like the relationship between silver and mithril silver.

"The nucleus of mercury, the neutrons of which are replaced by magicons, is the . So far, we only know that it comes from an island in the south."

"<>, right ......?"

Marcia muttered with interest. I guess she wants to go there.

"So, as for the properties of this <>, its physical properties are almost the same as mercury. Its specific gravity is about 13.5, and its melting point is about minus 39 degrees Celsius.

Other properties are almost the same as normal mercury.

"The chemical properties are almost the same, so be careful when handling it."

Jin emphasizes the danger of handling mercury, saying, "Especially when vaporized, it is easily absorbed through the lungs, and if absorbed into the body, it binds to hemoglobin and other substances, causing it to become toxic.

"Especially Saki."

He reminds her that it's more dangerous than the lacquer rash she got before.

"Oh, no, Jin."

Saki smiled bitterly, but her face showed that she understood.

"You have to be careful. It seems that when it builds up in the brain, the emotions become uncontrollable."

It was Jin who explained the case of Jix and Ganno.

"But what is definitely different from ordinary mercury is that it reacts to magic power."

He then went on to explain from the viewpoint of magical engineering.

"This metal transmits magic power very well. In this case, magical power refers to <> or >."

Stearina leaned forward.

"So it is very easy to this . That's why it was used in the Fluid Form Drive.

The advantages of not needing wiring of magic nerves and the ability to store mana are great. However," Jin says.

"The disadvantage is that the usable temperature range is narrow. It is also quite fatal. Apart from the toxicity of ......<>."

"Indeed. It can't be used in an environment where that ......<> is around, can it?"

Saki. When I once went to the Arctic Circle, further north of the demon territory, to search for the shell of the <>, the temperature was sometimes minus 40 degrees Celsius.

"Yes. And they are vulnerable to fire magic. ......"

It's also dangerous. Mercury vapors could be a terrible thing if they get into the area.

"I suppose it could be good for some purposes."

"Hmmm...maybe Jin could come up with a way to cover up such shortcomings?"

Unexpectedly, Marcia offered such an opinion.

"Well, ...... I'm sure there are a few ways."

Let's hear it, shall we?

"Well, I think there are a few things we can do. ...... For the low temperatures, we could build in a heater. That's easy.

Anyone can come up with that one.

"And for the high temperature, we can build in a cooler."

The overall efficiency will be a little lower, Jin added.

"That's right. ......."

Jin looks at him with difficulty.

"We can't do anything about the toxicity of mercury. At the very least, we'll have to find or create a safe liquid metal."

"That sounds interesting."

"Yes, that sounds interesting."

Saki and Toa's faces lit up.

"It's good to do research, but be careful not to get addicted.

Jin couldn't help but say.