"Elsa, I have a request."
At Jin’s words, Elsa replied with a smile.
"…I know. You’re planning to switch places with a Doppel, aren't you?"
"Spot on."
Jin offered her praise mixed with a wry smile.
"I want to examine that material as quickly as possible. I can't help but be bothered by that Phantom over there."
"Mm, I understand. Have a safe trip."
"It's not 'have a safe trip.' You're coming too, Elsa."
"Eh?"
"We don't know what might happen, so it's better if we stay together."
Jin’s decision was informed by the countless tropes he’d seen in anime and novels, where overconfidence—thinking things would be fine—led to a protagonist's girlfriend or family being kidnapped.
"Mm, okay."
With that, Jin, Elsa, and Reiko were enveloped in Invisible magic and headed toward Konron 3.
At the same time, Elm arrived there as well, carrying the armor fragment.
There were two security guards stationed at Konron 3, but thanks to the Invisible spell, they remained completely unaware of the group's movements.
After receiving the fragment from Elm, Jin silently used the Warp Gate inside Konron 3 to travel to Hourai Island.
"Welcome back, My Lord, Elsa-sama."
As usual, Laojun's voice greeted them upon arrival.
"Send out Doppels of myself and Elsa to take our places back at the venue."
"Understood."
After giving his instructions to Laojun, Jin hurried to the workshop, followed closely by Elsa and Reiko.
He placed the sample fragment on the workbench and finally began his analysis.
"So this is the piece of armor. It’s light…"
His first impression was its weight—or rather, the lack of it.
"It really is light."
Elsa also picked up the sample, her eyes widening in surprise at its weight.
"Now then, as for this metal…"
Jin had a single match for this in his memories of modern Japan. He could identify it even without using Analyze.
"This is foamed metal."
"Foamed metal?"
As Elsa repeated the term, Jin explained.
"Yeah. Though I only have a smattering of knowledge about it."
It was a material that had still been under development back in the modern Japan Jin remembered.
"I only know that they use gas or other agents to make aluminum or titanium foam."
He stared intently at the sample before him.
"The material is titanium… or 64 light silver. It has countless, microscopic holes throughout it. That’s why it has that matte finish."
Jin spoke honestly, admitting he didn't know the exact manufacturing process used here.
"Even you don't know, Jin-nii?"
Elsa couldn't hide her astonishment.
"No. Though it's not like I couldn't make something similar myself."
He added that there were several manufacturing methods he could imagine.
"For example?"
Elsa was clearly curious. Jin leaned back in his chair and began to lay out his theory.
"First, structurally, you just need to create countless tiny voids. In other words, you just have to create tiny bubbles inside the metal."
"Mm, I see."
"The problem is how to achieve that. One possibility is generating bubbles while the metal is in a molten state."
While a molten state usually required extreme heat, a spell like Softening could achieve a similar consistency at room temperature.
"…True."
"But ordinary bubbles wouldn't result in a foamed state this fine. So, as another possibility…"
Jin explained how one might use magic to create the bubbles.
"With magic, you should be able to create incredibly minute bubbles depending on how you apply the spell."
"Ah, I see. As expected of Jin-nii."
However, Jin shook his head.
"But this sample looks like it was made using a different method altogether…"
He crossed his arms and stared fixedly at the fragment.
"But Jin-nii, wouldn't this be… weak?"
At Elsa's question, Jin realized there was something he should have considered before the manufacturing process.
"Yeah, definitely. That’s why it shattered into fragments like this."
"Then why would anyone make armor out of it?"
"That’s the question."
The advantages of foamed metal included its light weight and increased heat resistance in certain alloys, but Jin felt it was fundamentally ill-suited for armor.
"It would certainly absorb shocks, but…"
That was the extent of its utility. Overall, its defensive power would be low.
Just then, additional information arrived from Laojun.
"My Lord, I have received a report from Elm at the scene. He says that the carriage carrying the armor was also loaded with barrels containing a very heavy liquid. Based on his observations, the specific gravity of that liquid is likely comparable to liquid metal."
"What!"
Jin stood up abruptly at the news.
He sat back down a moment later, but this time, a smirk played across his lips.
"Jin-nii? What is it?"
"…With that information, I think I’ve figured out the purpose of this armor."
"Eh?"
As Elsa tilted her head in confusion, Jin explained slowly, as if teaching a student.
"Foamed metal and liquid metal. Does that combination suggest anything to you?"
"…Um, it would soak in?"
"Exactly."
Jin gave a firm nod.
"Most likely, the armor's true performance is only unlocked once the liquid metal is allowed to permeate this foamed metal base."
"Its true performance?"
Jin gave a wry smile at her question.
"I can't say for sure since I don't have the liquid metal itself to test. However, I’ve come up with two theories."
"Tell me."
"Of course. The first is simple reinforcement."
"Mm, that makes sense."
"Right."
When you had porous metal and a liquid metal, it was a natural association to make.
"I think you could expect a dramatic increase in strength from that combination."
At the very least, that explained why even Jin hadn't been able to identify the material used for Phantom’s armor.
"It’s not an alloy, and it’s not plated. Because it’s in a 'permeated' state, the appearance is unlike anything else."
It was only natural that it couldn't be identified from a distance.
"However, while I’m prefacing this as a guess, I believe the second theory is the true objective."
"And what’s that?"
"It’s related to the very thing we’ve been chasing for a while now—"
Jin paused for a moment before delivering his conclusion.
"—the practical application of the Fluid Form Drive."