Tetra returned to Kuromueina's Castle in the Demon Realm, expanding her Magic Power Detection while in visibly high spirits.
"Ah, he’s here. I might as well pay him a visit while I’m at it."
Once her detection confirmed the individual was within the castle, she set off. After a short walk, she spotted her target: Zex.
"Hey, Zex."
"If it isn't Tetra-dono... You certainly seem to be in high spirits."
"I’ve been having the best time imaginable. My mood couldn't be better. Though, sadly... time passes far too quickly when I'm with him. It felt as though our time together ended in a heartbeat."
"I see. So you were meeting with Miyama-dono? I assume this visit relates to that?"
As a powerhouse of the highest-ranking Count-class himself, Zex understood that Tetra had sought him out specifically. Judging that she had business with him, he cut straight to the point. Tetra handed him a folded piece of paper.
"I want you to look at this first. It’s a temporary assembly for a magic formula. I can put them together to an extent, but I’m nowhere near your level when it comes to magic tool production. Please overlook any clumsiness in the structure."
"Hmm, let’s see... What?! This—this is...!"
"Now that you've seen it, let me explain the circumstances. It started with a conversation about the specialized brushes Kaito bought..."
Zex’s shock was exactly the reaction Tetra had anticipated. She detailed her exchange with Kaito—the tool attached to the brushes that performed magic power conversion, her viewing of it, and her subsequent attempt to draft the formula. She finished in a serious tone.
"The item Kaito had didn't use magic crystals; it seemed to generate magic power internally. It likely shares properties with the white magic crystals Kaito possesses, which makes it impossible for us to replicate exactly. However, the tool was constructed using a magic formula that aligns with our world's technical systems. It was likely adapted specifically for this world."
"And so you created a temporary assembly adapted for production using magic crystals... But this..."
"Exciting, isn't it? After all, converting one's own magic power wavelength into something else is a super-high-level technique. The Phantasm King-sama uses it often, but that’s only possible because of her peerless skill. I might be able to manage it to some degree, but I’m not confident I could hit the intended wavelength perfectly every time."
"Indeed. The formula would be far too complex. I had assumed it was impossible to even attempt adapting it for a mass-produced tool... and yet, to think such a method existed..."
"Apparently, the Spirit of the World Tree living at Kaito’s place was the one who thought of it. The concept is pure genius. They broke down the Magic Power Wavelengths Conversion into ten simple magic formulas, one for each step, and made it work by linking them together."
"It is truly impressive... The logic is sound. Normally, wavelength conversion requires the simultaneous execution of multiple processes: the decomposition of magic power, the erasure of the original wavelength, preparing the foundation for conversion, bestowing the new wavelength, and reconstituting the decomposed power. Performing all that at once is what makes it so impossibly complex. Simplifying it by splitting the steps into separate formulas, then performing linking and synchronization in sequence... well, it’s one thing to say it, but quite another to find the correct points to divide the formula. Usually, it would take years of dizzying trial and error to arrive at such a perfect answer."
The formula structure was incredibly refined. Repetition of trial and error over a vast amount of time would have been the only way to reach such a perfect, beautiful configuration. Seeing how the processes were partitioned and the order in which they were combined was enough to make an expert like Zex sigh in admiration.
"If I recall correctly, the one who devised the method of making magic formulas function while partitioned was also that spirit girl, wasn't it?"
"Yes. It was likely Nebula-dono who devised the concept, and Canalis-dono used her omniscience to derive the exact steps, resulting in this final form. But the initial inspiration is magnificent. Seeing it laid out like this makes the answer seem obvious, but I doubt I could have ever arrived at this idea myself. Perhaps she only thought of linking multiple formulas to produce a greater effect because she had already devised the Partition Formula? Regardless, I must take my hat off to them."
Tetra nodded in agreement with Zex’s heartfelt admiration, then shifted to a serious demeanor.
"Now we come to the main point. Zex, I want your expert opinion. After seeing this, I’ve judged that we can imbue magic tools with a formula for magic power conversion—turning poured mana into any arbitrary magic power. Do you agree?"
"It is possible. Of course, we’ll need some trial and error to modify the formula for a magic tool, but since the hardest part has already been answered, it shouldn't take much time at all to create a tool capable of magic power conversion."
"I’d like to ask based on that premise. Here are the applications I thought of off the top of my head: 'A user can pour in magic power to allow even low-purity magic crystals to trigger high-consumption formulas,' 'magic power consumed by a tool can be replenished manually without waiting for natural recovery,' and 'it becomes possible to trigger formulas that were previously impossible to activate even with black magic crystals.' Do you think those are feasible?"
"...They are indeed possible."
A massive revolution was quietly brewing in the world of magic tools.
Serious-senpai: "...Did you catch all that?"
~~
Kaito: "If you're turning that item into a magic tool, please get permission from the Sharon Count House."
Tetra: "Understood. I'll make it a joint development."
Kaito: "All right, then I'll leave it to you."
Tetra: "Sharon Count House-san, let's start a revolution in magic tools together!"
~~
Serious-senpai: "...Good grief. Cornelia’s stomach is dead."