On the morning of July 19, Jin, Erza, and Saki went to Horai Island. Bertsche went back to the village of Kaltz where Reinhardt was waiting for her.

Stearina was on Horai Island. She had been coming here since she returned to her home in Gore, Kingdom of Selroa on the 16th.

"Hello, Mr. Jin, everyone."

Stearina had taken a room on the third floor as her laboratory. Then Jin and the others showed up.

"What's the matter today?

"I had a topic I wanted Stearina to think about."

"Well, what is it?"

Jin talked about artificially creating magi crystals. Stearina jumped for joy when she heard this.

"Okay!　That's what I wanted to do!　I love crystals, beautiful gems, and magi crystals, but they are not the materials to make a golem!

So, once again, we get down to the nitty-gritty of the story. The first to open his mouth was Jin.

"There is a that is often used for golems, right?　They store mana in magecrystals. Do you know how it works?"

"Yes, ......, I'm ashamed to admit that I don't know how to use it."

There are two types of technology, one is derived from empirical knowledge and the other is derived from theoretical knowledge. One of the techniques, discovered after a long process of trial and error, was the mana tank.

"Please think about how mana can be stored in a mana tank.

"I don't ...... understand."

After thinking for a while, Saki gives up. After thinking for a while, Saki gave up. So did Stearina. But Erza was still thinking. Eventually Erza looked up and answered in a small voice, sounding unsure.

"Do you think I can get into the ...... gap?"

"I think that's the right answer."

Jin guessed Erza's answer, and knew she was thinking along the same lines as he was. Saki and Stearina, however, kept their heads tilted. Jin then began a simple explanation.

"Inside the box, you fill a large round stone. Now, when the box is full of round stones, will there still be room for anything else?

"Hmm?　If it's full, it won't fit anymore, right?　...... No, no. No, no. Sand would still fit in the box.

Jin nodded at Saki's answer.

"That's what I meant. Sand, I mean, water could fit in there too, couldn't it?　In other words, there's room for something of a different size.

Stearena opened her mouth to speak after this explanation.

"Does that mean that mana is very small?

"I think so. All matter is made of something called <>. Molecules are tiny particles that you can't see, but mana is much, much smaller than that. And I guess that free magic element (ether) is even smaller.

Jin explains his theory.

"I think that although free magic element (ether) and magic element (mana) can enter almost any substance, the substance which can contain a lot of magic element (mana) and yet is easy to take out is a magic crystal. Of course, since the magic formula can be written directly into the magecrystal, it's also more efficient for use as a tank.

"I see. I'm following along. I'll have to ask you to explain the word "molecule" or something like that later. ...... please continue."

"Now, what if we put a lot of mana into an ordinary stone and keep it there?"

"...... become an artificial Magi Stone?"

Now Saki spoke up with a theory. Jin nodded.

"...... if we could. Unfortunately, it didn't work when I tried a little earlier.

"I see. Even gin didn't work. ......"

Saki's shoulders slump. But Stearina was determined to fight back.

"But that's exactly why it's worthwhile!　You mean we have to find out what magi crystals are and how to make them, right?

Jin nodded,

"Yes. Let's try some things first."

He asked Reiko to prepare a variety of magi crystals.

"First of all, I'm wondering if we can figure out something about why the magi crystals have different colors depending on their attributes. ......

Jin said as he looked at the multicolored magi crystals on the workbench.

"Well, of course that's true, but what's the difference between Magi Crystals and Magi Stones?　Is it just the amount of mana contained in them?"

"Magi crystals are mostly transparent or translucent, while magi stones are opaque. I think there might be something there.

"Oh, maybe."

Erza seemed to have an idea when she heard Stearina's comment.

"Magi crystals are <, I think. In other words, since the molecular arrangement is regular, it's easy for mana to get into them. But that is not the case with magi stones."

Saki and Stearina, who did not know the true meaning of the word "crystal," did not seem to understand the statement, so Jin gave a supplementary explanation.

"Crystals, as we call them, are the molecules ...... I mentioned earlier, the small grains that make up matter, arranged in a regular pattern. Like hexagonal prisms for crystals."

Both of them nodded their heads in agreement with Jin.

"On the other hand, you could say that the gaps are neatly lined up. Straight roads or winding roads, which is easier to drive on?

"That's right, brother Jin. I could not have come up with that analogy.

At least, the crystalline nature of the material seems to be a major factor in whether it contains mana easily or not.

"Then, the next question is whether mana can naturally enter such stones and crystals.

If we can understand the process and reproduce it artificially, we may be able to create artificial magic crystals (magi crystals).

"Is that something we can understand by ...... thinking about it?"

Saki sounded unsure.

"Well, I think we can find out a little something by thinking about what kind of place we can find it.

"What kind of place, you mean?"

"Yeah. As far as I know, it is my experience that fire magic stone can be found near the volcano in the village of Kaina. I have also found magi crystals of the earth attribute.

This was last year.

"Underground of Horai Island, all the attributes can be extracted, right?

Jin nodded at Erza's words.

"Yes. Apparently, there is a point where there is a high concentration of free magical element (ether) under the island.

At that moment, Erza again had an idea.

"...... free magic element (ether) combined into magic element (mana)?"

"What?"

Hearing these words, Jin involuntarily stared at Erza. Erza turned her head slightly to meet Jin's gaze.

"I see. ....... If free magic element (ether) is an atom, then magic element (mana) is a molecule.

Erza understood Jin's muttering.

"Yes, that's what I meant.

Again, since the two could not follow, Jin had to explain.

"An atom, ...... well, it's like a block of wood. By themselves, they are just pieces of wood, but when you put them together, they become a house or a castle.

The analogy seemed to make sense.

"I see!　Fire, water, earth, and wind ...... each have a specific combination of free magical elements (ether), is that right?"

Saki said happily, and Stearina also said happily,

"So it's magic and spells that create that combination!"

Both of them were familiar with the concept of free magical element (ether) and magical element (mana), which was a big help for Jin since he didn't have to explain it to them.

"Oh, maybe the gaps between the crystals are shaped like the magical element (mana) of each attribute, and these are the magi crystals (......)."

The theory that Jin had developed seemed to be on the right track.

It could be described as a positive and a negative, or a male and a female form.

Jin hypothesized that a magi-crystal is a crystal in which free magic element (ether) is incorporated into a crystal whose shape of the gaps between the crystals is just like the shape of the magic element (mana) with each attribute.

The problem is that all the attributes are not well explained, but the rest of the explanation makes sense.

"If that's the case, there must be such a thing as a magical crystal (magicrystal) without magical element (mana), right?　I've never seen such a thing. ......"

"It's quite common to find a Magi Stone that has lost its mana, though."

Stearina and Jin nodded their heads.

"A Magi Stone that has lost its mana is just a stone, isn't it?"

"Yes. But the color may become a little lighter. ......

Jin looked unsure of himself, since he didn't use magi stones very often.

"Why don't you try it then?"

Erza said. Surely, if we don't know what will happen to the Magi Crystal without mana, we should experiment with it.

"Okay, let's give it a try.

So, I decided to use the smallest magi crystal on the workbench as an energy source, and to invoke some kind of magic. It would be better to use as much mana as possible.

"Okay, I want to use a magijammer.

Indeed, it is a magic tool that consumes a lot of mana.

Jin asked Reiko to bring him a prototype. In the meantime, I will briefly explain what a magijammer is.

"Hmmm... it interferes with the activation of magic. That's very interesting.

Jin, you've even developed such a thing!

Father, I've got something for you.

While we were talking, Reiko came back.

She said, "This is an ether converter, so you'll have to modify it. Then I went to ......."

By partial modification, the system was changed to one that uses magic crystals (magi crystals) as an energy source. At the same time, the intermittent drive to reduce the consumption of magic power was stopped, and the drive was made to be continuous.

"Okay, <>."

Jin activates the modified magijammer.

"If you stay on this side, you should not be able to use magic anymore.

"Really?　I'll give it a try. ......<......Oh, no. I really can't use magic."

"Well, that's interesting. I'd like to hear more about it later."

Saki is especially interested in the origins and effects of magic. This is evident from the fact that her thesis on alchemy was also on <.

The magijammer, which had been modified to increase the consumption of magic power, stopped working after about 10 minutes.

"Okay, let's see what's going on.

Jin checked the part of the Magijammer that was supposed to contain the magic crystal.

"This is ......."

There was nothing where the Magi Crystal should have been.