Core and Kernel: The Fundamentals
"Everyone noticed the difference, right?"
"...Thanks to you."
"S-sorry to Seyul, but... Yuri's definitely faster."
"Ahem. It's only natural. I didn't earn the title of top student in the entire school for free."
The multi-casting the little one demonstrated was clearly different from the class president's. The flow of magic was smooth as water, and the casting speed was much faster. This felt natural to me. It meant the little one's multi-casting technique was more familiar.
I looked at Salbyeol.
"Why... why yoyo?"
No matter how much of a magical genius the little one was, she couldn't have invented advanced multi-casting on her own. There must have been help and guidance from Salbyeol.
"Anyway, as I said before, the reason the little one's multi-casting is fast comes down to core optimization."
"You said we can't do that right now."
"The class president is right. So today, I'll give a supplementary explanation about the core—more precisely, about the kernel and the core—that I couldn't go into detail on before. It won't be enough to actually transform your cores, but it should give you plenty of hints about which direction to head in from here."
What I was about to explain to the kids was part of a university-level major course back in Magica. Of course, I planned to keep it as simple as possible, omitting anything too complicated while considering their intellectual level, but even so, some parts would still be difficult for them. The one reason I wanted to cover this anyway was simple: to establish a solid foundation.
If I tried to explain things too easily and briefly, misunderstandings and distortions were bound to appear. I couldn't just brush them off with "That's just how it is." People accept things at vastly different levels. Some grasp the concept of "1+1=2" right away, while others struggle to accept why it has to be 2 in the first place.
Besides, countless hidden meanings lie behind the things we usually take for granted. An apple falling to the ground is obvious, but the law of universal gravitation explains why.
I held up both index fingers and spoke.
"Earlier, I didn't distinguish between the core and the kernel, but the difference between them is actually clear. What exactly is it?"
"Hmm......"
The kids' expressions grew thoughtful at my question. The little one looked like she knew the answer, but she held back, probably out of consideration for the class president and Miju, who were still thinking. She might be young and eager to show off, but she wasn't completely lacking in tact.
Yawning, I waited for their answers.
"The c-core has substance! The kernel doesn't... n-no, wait?"
"I think something similar. The core actually exists, while the kernel doesn't—it's more like a concept."
I had planned to slack off a bit more, but their answers came faster than expected. They were even surprisingly close to the correct answer.
"Close. It's true that the core is a tangible unit inside the body that can be observed with the eyes. Every magical girl absorbs, stores, and transforms mana through her core. So the two of you are right that the core actually exists. But there's something missing from the rest of your explanation. What could it be?"
"Uh..."
"If what you said about the core is correct... then the explanation about the kernel must be wrong...?"
"Specifically, how?"
"...Well, um."
"I-I don't know..."
That was enough thinking. I decided to give them the answer.
"The kernel is a mediator that helps the core function correctly, and it's the actual law that allows the core to operate efficiently. In that sense, the core alone cannot understand the magic circles we draw. Everyone, try recalling the magic circle for Magic Missile. Doesn't it seem strange? Why is the magic circle designed to be easy for humans to understand?"
"...Now that you mention it, yeah."
Even the little one looked blank, as if she hadn't considered this part.
"The reason the magic circles we casually draw can activate properly is all thanks to the kernel. The kernel interprets the magic circle and passes it on to the core. The core simply implements the magic based on what the kernel has interpreted. In that sense, the kernel can be seen as an excellent mediator connecting the core and the magical girl."
"It's like an interpreter who translates in the middle?"
"Exactly. It's easier to think of it as an interpreter. Class president, one praise sticker for you."
"I-I'm jealous... A praise sticker from Jihye..."
"Well, it's better than not getting one, but... is it really something to be jealous of?"
"Unni... I'm jealous of the praise sticker."
"Yuri, you're jealous of that? Really?"
"Yeah! Unni, how many praise stickers do you have now?"
"Just one now. By the way, Miju next to you has exactly one as well."
"Hmm... Then I'll overtake you soon, right?"
The little one suddenly burned with determination. She looked full of enthusiasm to earn a praise sticker. There was no actual benefit to collecting more praise stickers, but the tutoring group had somehow turned competitive. The class president had seemed ready to back out at first, but the little one's rival declaration had clearly made her uneasy. At least it would help them focus more on the lesson... probably?
The overheated atmosphere worried me a little, but I continued explaining with a calm expression.
"And on a larger scale, the kernel is also the law that makes the core operate effectively. If the kernel is flawed, even a well-structured magic circle might produce worse results than a roughly made one."
"So in the end, to make multi-casting faster, my kernel needs to change?"
"Multi-casting is a bit more complicated. You have to adjust both the kernel and the core at the same time."
"Ah..."
The class president couldn't hide her disappointment.
"That's why multi-casting is so difficult. You need to understand both the core and kernel concepts precisely, and even if you haven't experienced it yet, you'll definitely run into race conditions. Handling those is pretty complicated, so it's hard to explain right now. But if you keep up, you'll be able to do it someday, right?"
"R-right. You can do it. If it's Seyul."
"Jihye unni said that, but it's actually not that hard. I can guarantee it."
The class president's disappointed expression softened a little at her friends' comforting words. Seeing this made me wonder if outstanding magical girls were just born with kind hearts too. The theory of magical girls' innate goodness came to mind.
More importantly, little one. You can do it easily because you have Salbyeol as your mascot. Normally, magical girls without mascots find multi-casting difficult. But since Salbyeol refuses to reveal himself, I couldn't explain that the little one's achievements owed a lot to her mascot's help.
And the class president would compare herself to the little one and attribute everything to talent. Of course, she wouldn't be blinded by jealousy and suffer over it, but you never know. This was something I needed to keep an eye on. Miju included.
For some reason, in this world without magical girl mascots, I couldn't carelessly expose Salbyeol to others.
Whew. Explaining while thinking at the same time was making me a bit sleepy. But we hadn't even reached the main point yet. I had no choice but to sit back down and continue the lesson.
"Like this, you can modify the kernel and core to suit yourself, allowing you to use faster and more varied magic. And someday, there will definitely come a day when you need to transform your kernel and core. But not now. Right now, building a foundation comes first. If you understand the basic kernel and core well, it'll greatly help develop your magical abilities. The same goes for martial arts, of course."
I added at the end that there was no need to feel discouraged already. It wasn't specifically meant for the class president or Miju to hear.
"Even the basic kernel and core alone are complex enough and have diverse uses, so studying them isn't easy. There are also concepts that branch out from here, so studying is obviously essential. In short, it means the little one needs to study too."
"Okay! I will. Of course, I could finish it all easily if it were me."
She really had incredible confidence. Was it because she was young, or because she trusted her own talent so much? Or maybe she was just naturally optimistic.
The little one didn't stop there. She looked around and added,
"You unnis can do it too, right? We're friends, after all."
At the little one's words, the class president and Miju smiled and replied.
"Yeah. If we take it slow without rushing, we'll get there."
"Right. So as long as we're with Jihye and everyone, we can do it."
In the middle of this warm atmosphere, a sudden thought struck me. Was this... really a friend relationship? Of course, they were friends with each other. But no matter how I thought about it, I didn't seem to be included. At some point, I felt like I'd simply become a private tutor. Friends, my foot—this was more like a teacher-student relationship.
The way the kids looked at me was too bright. Yeah, friends teach each other things they don't know. I found myself brainwashing myself like that.
Yaaawn.