Chapter 21: Magic Circle

It happened about a week after we discovered Hihiirokane.

「Hey, hey, Sensei! Look, look, loooook!」

At the racket of flapping and Rin’s cheerful voice, I turned—and she literally leapt at me.

「Rin!? What’s up?」

Catching her reflexively, I opened my eyes wide in surprise.

A girl in a wheelchair shouldn’t be able to jump.

「Ehehe. This, this!」

I looked where she pointed after springing away. There, spreading out like a skirt, was a large waist fin. It had certainly grown over the ten years since we met. Lately she’d managed to walk a little, but the one before me was clearly larger than it had been just yesterday.

「A growth spurt…!?」
「You know how Sig made a sword the other day?」

At the abrupt shift in topic, I nodded.

「I thought, oh, you can change shapes—so I tried it, and it worked.」

Struck speechless by Rin’s concise explanation, I said nothing.

Looking closely at the waist fin, it was larger, but the number of rings was unchanged.

「…Rin. Please, when you cast magic on your own body, do it when I’m with you.」
「Okaaay!」

Rin threw up her hand with a bright “aye.” She is obedient, that much is true.
But jumping straight into human experimentation on herself—bold, or just fearless…

「Sensei, what are you doing? What’s that?」

Tilting her body to the side, Rin peered at what was behind me as she asked.
What sat there was a clumsy, igloo-like thing made of packed earth.
A hemispherical mound of earth had a gaping hole, and inside a flame roared.

「It’s a kiln.」

Thanks to the other day’s discovery, we now knew metal existed close at hand in large quantities. But that didn’t mean there were no problems. Most of what we gathered wasn’t in crystalline form like what we found at Hole Mountain; it was ore—metal mixed with rock.

「I’m trying to melt out just the Hihiirokane with this…」

To extract only the pure metal, you melt it—or so I think. Metal melts at a lower temperature than rock, so if you heat it, only the metal part should ooze out… something like that. Probably.

Working from such hazy knowledge, I put together this misshapen kiln.
At first I tried to melt it by applying fire directly, but the full-power flame I hadn’t breathed in ages, in dragon form, effortlessly vaporized the entire Hihiirokane ore.

Then I figured I’d hold back and produce fire in human form, but no matter how much I heated it, there was no sign of anything melting out.
I was struggling to produce a temperature somewhere in between.

With magic, producing a stable output is incredibly difficult. You can modulate to a degree, but keeping a fixed temperature or sustaining constant power just isn’t easy—and even if you manage, it’s exhausting. It demands extreme concentration and stamina.

It’s like trying to keep a dandelion tuft floating on your breath. You can blow harder or softer, sure—but blowing at exactly the same strength to hold the tuft at a single point in midair is a herculean task.

So I decided to lean on non-magic technology: instead of heating directly with magic, raise the temperature in a kiln and melt the metal. With this method, I should be able to raise the heat without overshooting…

「Waaah!」

My shallow plan blew apart along with the exploding kiln.

「Amaaaazing! Do it again!」
「That was a failure.」

I slumped my shoulders and sighed at Rin’s excitement.
Bad structure or bad materials—whatever the reason, once the temperature passed a certain point, the kiln exploded before the Hihiirokane could melt. No matter how carefully, how slowly I raised the heat, the result was the same.

For the kiln body I’d used properly dried clay like earthenware, and I’d even reinforced its strength with magic, but… With my hazy knowledge, it seemed I simply couldn’t build a kiln that could withstand melting metal.

「Why don’t you ask Luka how to do it?」
「…Luka?」

When I parroted the question back, Rin nodded. “Mm-hmm.”

「Luka’s good at that kind of thing.」

True, her magic is extremely stable. In terms of raw output she’s second from the bottom—next to Sig, her Four Elements measurements are the lowest. But her output hardly wavers.

I’d chalked it up to inborn talent—personality or race—but maybe there was a trick to it.

「Alright, let’s ask her.」

Together with Rin, I headed into the school building. Luka happened to be chatting with the other students.

「Ah, Sensei, what br— Huh!? Rin, you’re walking on your own!」
「She really is!」

Luka noticed us first and stared, wide-eyed, at Rin pat-patting along by my side.

「Hey, how’d you pull that off!?」
「Amazing, right!」

At Sig’s shout of surprise, Rin puffed out her chest with a proud little “ahem.” It seems she came to show me first. It’s simple, but it makes me… no, it makes me really happy.

「Luka, could you teach me something? Is there any trick to stabilizing magic?」

After Rin finished showing everyone her magical feat, I broached the topic with Luka.

「A trick…?」
「Yeah. You’re really good at keeping magic stable, right? Me… well, I’m like this.」

“Light, kindle small at my fingertip.” I chanted briefly and produced a flame—yet blinding light gushed from my hand and swallowed the surroundings in an instant.

「I said at my fingertip!」

As I shouted and clenched my hand, the light subsided like a doused flame.

「Uuugh, my eyyyyes…」
「As ever, your magic is tremendous, Sensei.」
「Your control’s a total mess, though.」

Rin clutched her eyes with both hands—she must have looked straight at the light—Violet-san voiced her admiration, and Sig added that with a touch of sarcasm.

「Oh, shut it. You’re not that good at it either, Sig.」
「I’m better than you, Sensei.」
「Then show me.」

Trading barbs, I urged Sig on. He didn’t seem to mind. “Sure,” he said easily. The fact we can joke like this now counts as progress.

「White one, dazzling one, shining light—be in my palm.」

With the spell, light was born in his hand. It swelled and shrank as if it were pulsing, then fizzled out.

「Not much better than Onii-chan, is it?」
「Ugh…」

At Yuuki’s blunt verdict, Sig and I groaned in unison.

「Then, Luka-chan—if you would.」
「Uh… Light.」

Urged by Violet-san, Luka cupped her hands like a bowl and chanted a single verse. That alone made a ball of light rise in her palms. It wasn’t blinding like mine, nor did its brightness fluctuate like Sig’s. Above all, its shape was beautiful.

The light sphere Luka created was nearly a perfect sphere—like a full moon in the night sky. By comparison, Sig’s light flickered like flame and its outline was indistinct. Mine likely looked the same from a distance.

Violet-san and Yuuki were far better than us, but even they couldn’t stabilize it this well.

「I got it!」

Rin suddenly cried out.

「If you make your hands this shape, you can do it better!」

She pointed at Luka’s neatly aligned hands.

「No way it’s that simple…」
「Light!」

Cutting Sig off, Rin copied Luka—putting her hands together and shouting.

「You’re kidding…!?」
「My.」
「Awesome!」

Sig’s eyes bulged, Violet-san brought a hand to her mouth, and Yuuki cried out.
What had appeared there was a distorted sphere of light.

Distorted, but unmistakably a sphere.

When it came to stability, Rin was by far the worst among the students; in exchange, her output was high—a trait very much like mine.

And now Rin, however roughly, had managed to stabilize a spell.

「L-Light! …Oh!」

Sig immediately copied her and put his hands together. A small, spherical light formed above his palms, and he let out a gasp of admiration. Violet-san and Yuuki followed suit and likewise confirmed their spells stabilized. I never would have guessed it was something this simple.

「Light!」

Overjoyed, I put my hands together and shouted.


An instant later, the classroom was flooded with light and we couldn’t see a thing.


* * *


「My eyes are still dazzled…」
「Yeah, seriously—sorry.」

I bowed over and over to Yuuki and the others as they winced and blinked.
Apparently my magic had been highly diffuse.
Stabilizing and concentrating it had produced enough luminosity to blind anyone who saw it; even though I’d snuffed it right away, the students were still complaining of eye trouble some time later.
As for Rin—maybe she’s sensitive to light—she, usually so lively, was slumped with her eyes shut. At least it didn’t look like there was any risk of actual blindness, which was a relief…

「Still, who would’ve thought hand shape could change a spell’s stability.」

Magic generally comes out of the hands—or to be precise, from a point a little off the hands. But I’d never paid any attention to hand shape. Everyone had been using whatever shapes they liked, and there’d been no inconvenience at all.

「Sort of… I’d imagine it coming out sized to fit in these hands, and cast that way.」

Her eyesight recovered, Luka cupped her hands again as she spoke.
Sure enough, the light sphere she produced was about the same size as her cupped palms.

「Ah. So that’s it. Having a size reference does make it feel easier.」

Violet-san cupped her hands again and produced light.
Perhaps because she now understood the principle, it was even more stable than before.

「I see.」
「Don’t do it again, okay!?」

I reflexively mimed cupping my hands, and Sig hastily nailed me with a warning.
Even I’m not foolish enough to make the same mistake twice.

「A size reference, huh… Luka, how many centimeters is your hand?」
「Ah!」

At Yuuki’s offhand question, I couldn’t help crying out.

「What is it, Onii-chan?」
「That’s it! That’s it, Yuuki!」

In my excitement I seized her hands and shook them up and down.

「Violet-san, could you produce a vine? Any length is fine.」
「Very well… here you are.」

I tied one end of the vine Violet-san produced to a wooden stick and the other to a lump of charcoal. Then I dotted the desk with the charcoal, set the stick there, pulled the vine taut, and swung it around. In other words, an improvised compass.

A clean circle appeared on the desk. I could draw this much freehand, but being able to identify the center is probably better.

「Luka… no.」

If it’s Luka, it might be too clean to see a difference.

「Yuuki. Try making light that fits inside this circle.」
「Okay! —Light.」

Quick on the uptake, Yuuki must have grasped my intent at once. She deliberately aimed a single hand at the circle and spoke a short spell. The light rose not from her palm but above the circle—a beautiful sphere like a full moon floating in the dark.

A circle. It’s the simplest magic circle there is.
And I grasped, by intuition, what magic circles meant in this world.

It’s a ruler for magic.
Not for measuring length, but for drawing straight lines.