Jin and Marikka were discussing in a room on Onogoro Island.

Marikka's automata, Hanako, is serving them.

This time, Reiko is quietly behind Jin.

"...... that was a surprise, wasn't it?"

"Yes, Jin-sama."

The two were recalling what had just told them about the events from the time of the < to around the time of Adriana Tierra.

"I could only approximate it, but ......"

"Yes."

"Once there was a period of considerable decline. ......"

"I guess that's just the way it is."

<, the first who ruled was gone, and the more generations passed, the more magical tools and magical machines stopped working due to their lifespan.

The standard of living also gradually declined, and the lowest settlements were so low that they could not even produce magic tools.

On the other hand, in the communities where maintenance personnel existed, it is said that they no longer made new magical tools and machines (magi-machines), and that they only experienced a slight cultural and humanistic regression.

That was about 2,500 years ago.

After that, the blood of the <> faded away, and a new race of people called the <> emerged, and civilization began to progress once again.

Most of the technology of the <> became lost technology, and the settlements of the past were left behind in the form of <>, which occasionally brought advanced technology to Ars.

A very small number of have managed to maintain a slight advantage over the general , with a smaller decline than the general .

One of them is the settlement of <>, the ancestors of <>.

The other is the current Federation of Nord.

"......, though I don't know the details of the transition."

"That's right, isn't it? also seemed to be indifferent or uninterested in the outside world.

"I guess it's also because the outside world was technologically inferior."

"Yes. It was so inferior that it could not be considered a threat.

After that,......400 or so years ago, the technology had developed to such an extent that it could not be ignored, so <> sent <> to investigate various things and found that the world was not as good as it had been in the past. After an encounter with and his colleagues, we have come to the present day.

"I realized that any technology, if it loses its background, ...... or its foundation, ...... or whatever, it will decline."

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

The achievements made by Jin 400 years ago have been almost completely erased by the destructive forces of the <>.

This may be one of the rewards for only giving achievements and neglecting to raise the level of technology.

It was not good enough for him to just give and leave it at that.

It was the descendants who took refuge on that inherited Jin's technology.

"This time, we'll take our time."

"We can do that, can't we, Jin-sama?"

* * * * * *

Now that his business was settled, Jin wondered how Daiki-Kona and Mrs. Daiki-Kona were doing.

Marikka asked the automaton <> who was in charge of the above-ground facilities on Onogoro Island,

Yes, Marikka-sama. Yes, Marikka-sama. At the moment, they are enjoying touring around the island.

She replied, "That's all right.

"That's all right then. We can stay the night and go back tomorrow.

The old man was keeping an eye on Reuzert's house with his peepers, so there was nothing to worry about.

"So, would you like to see Rubina and the others?　I'm sure they would love to meet you."

I will.

I will.

When Jin went to the section where Rubina and the others were, he was welcomed with open arms.

"Jin-sama!　Long time no see!

We just met on New Year's Day.

It's already been a week.

Well, that's true, but...

Happy New Year, Master Jin.

Oh, yes, yes. Happy New Year."

Jin wished all the participants a Happy New Year, as some of them had not yet said New Year's greetings to each other.

"What were you doing at ......?"

"Preparing for the airplane competition, of course!

"We have a large wind tunnel, so our experiments are progressing well.

Rubina's words were supplemented by Gulina.

"Oh, I see. Well then, we can look forward to the next time."

"Hey, Jin-sama, are you going to be there?"

"Well, I'm a little busy, so it might be difficult to make it."

"Well, ......."

Seeing Rubina's shoulders drop, Jin hurriedly adds, "Oh, but....

"Oh, but you can at least have a one-on-one battle with the winner.

"Oh, really?"

"Yeah. My plane might not fit our regulations slightly, though."

I'm sure they haven't changed it since the last time.

"Then you'll be fine."

I'm looking forward to it!

"I'm going to win this time!"

The declaration that the winner and Jin's plane would be able to battle one-on-one seemed to be a great reward for the participants, and they all seemed to be more motivated than ever.

The participants seemed to be motivated even more.

"Are there any problems?"

<, so Jin decided to ask for their advice in earnest.

"Well, Jin-sama, may I ask you something?

"Gurina. What's wrong?

Yes. I have a feeling from the wind tunnel test that we should make the wings smaller to increase the speed, is that correct?

"Yes, I think that's a good idea. ...... But if we do too much, the performance at low speeds will be reduced and it will be difficult to take off and land, so it's a trade-off."

"Oh, I guess you're right. I understand. Thank you very much.

Although Jin is not an expert on aerodynamics, he still seems to be a man above the rest in terms of knowledge and experience.

However, Jin felt that if they continued to work hard at this rate, they would be surpassed in the near future.

"May I ask you something?"

Shu, what is it?

Yes. Well, there is something called a "tip-tail plane," but I'm not sure of its advantages at this point.

"Oh, I see. I don't know much about it myself, but it seems to have a good elevation rudder. On the other hand, I guess you could say that the stability is not so good.

In the case of a tip-and-tail wing aircraft, for example, positive (upward) lift is generated when the nose of the plane is raised. This is in the same direction as the lift of the main wing, so it works well.

In the normal configuration, when the nose is raised, a downward force is generated on the tail wing, which is opposite to the lift of the main wings.

"The other disadvantage would be that the airflow generated by the leading tail would reduce the efficiency of the main wing."

"I understand."

As Jin, he couldn't answer what he didn't know, but he could still give his opinion.

The island of Onogoro at 3902 is also very active.