One meter is the distance covered by communication magic

through a fetish in 1/299,792,458th of a second.

—The 22nd International Weights and Measures General a.s.sembly, Dragon Year 5463

“That which is hot, which is red, o’ fire. Gather in my palm.”

The whispering, high-pitched voice of a young boy could be heard coming from the schoolyard. The sun still hadn’t risen.

“Morning. Giving it your all so early, s.h.i.+g?”

“—…! Oh, Mentor? You surprised me.”

Jumping at my voice, s.h.i.+g turned around with an embara.s.sed look.

I wasn’t sure when he’d started doing it, but I recently noticed that he’d been secretly practicing magic by himself in the morning.

“… I really just can’t get my head around these magic flames.”

s.h.i.+g muttered, looking at the small flame floating above his palm. It shook somewhat before whiffing itself out. The flames he produced weren’t able to stabilize.

It’s the same with how my compatibility with fire is too good, controlling it doesn’t go so well.

“But they’re lasting longer than before, right?”

s.h.i.+g’s expression grew mixed in response. He was someone who usually stayed away from others, but this expression of his was easy to get. At the very least, he didn’t seem happy.

“I am hard. I am fast. I am agile. I am heavy. I am strong…”

Layering up various incantations on himself, s.h.i.+g clenched his fists. Controlling reinforcement magic was a difficult thing. However, as far as he was concerned, that was nothing. Taking a step forward, s.h.i.+g thrust a fist out toward me.

After being trained by Yuuki, the way he carried his body was so smooth that his former self couldn’t compare.

—I caught his fist. Not as a dragon, but in my human form.

“Hey, Mentor.”

He was getting stronger. There was no doubt about that. But even so…

His progress was too slow.

“When, when will I be able to win against you…”

I didn’t have an answer for him.

“I think it’s about time we started farming large scale this year.”

“Really!?”

Yuuki’s response wasn’t surprising.

It had been around five years since we started this special cla.s.sroom. We’d been trying to cultivate plants on a small scale since the second year. It all withered on our first attempt, but the second attempt and on has been successful, with each harvest yielding more than the last.

Even so, there was a reason that we hadn’t started seriously farming on a large scale.

“If we’re going to do this seriously, we’ll have to prepare a large field.”

“Ugh… we’ll have to do that again…?”

She seemed to be thinking back to what we’d had to do. Yuuki frowned in reluctance.

Digging up dirt to till it, as well as the deweeding and stone removal were all necessary steps. Even just a small field took a considerable amount of work. Let alone heavy equipment, we didn’t even have the more common farming machines or tools.

“How big will it need to be, I wonder?”

“Yeah, that’s the first problem to figure out.”

I nodded in response to Violet’s question. How big do we need? Even now, I still don’t have the means to give an answer to a question like that. The reason being that I still haven’t decided on a basic measurement. Not just for length either, but for weight and volume as well. I haven’t made any progress in deciding on our system of weights and measures at all.

Of course, since we’re using j.a.panese as our language, we can still use words like meter and kilogram. Still though, saying exactly how long a meter is is what’s stumped me.

If I recall, the meter was based off of the size of the Earth or the speed of light. That said, it wasn’t like it was easy to settle on, making it so that they had to keep a close eye on its establishment.

Extreme accuracy is unnecessary at our level of civilization, of course. For example, saying something like a foot is easy to understand because its name implies that it’s based off the size of a person’s foot. Although it is easy to understand, using it in this world comes with its own problems.

The fact that our body types are so different being the first to come to mind. Lizardmen never stop growing and just continue slowly getting bigger, while lykoscentaur, similarly to wolves, only touch the ground with the tips of their feet, so deciding whether it’d be foot or leg size becomes its own problem. Then there’s merfolk, who don’t have feet at all.

It’s not limited to difference races either, it applies to humans too. Compared to humans on Earth, the humans here are much more varied. Although having a giant on Darg’s level is still rare, there’s still many who are considerably tall or, on the other end, short.

“It’d be nice if there was something that always had the same length…”

I could use things like stones or trees standards, but stones are heavy and difficult to use, and trees fade away before you know it.

“There is though?”

I looked at Nina as though to ask her what she was talking about.

“I’d be happy if it was something that didn’t change in length over a century or two, but…”

“It doesn’t change though?”

Huh, was there something like that?

I tilted my head.

Nina didn’t look like she was changing, but even she was growing ever so slowly. She’s gotten the slightest bit taller since I met her, and she’s matured.

“In at least these five hundred years, you haven’t changed at all.”

“Huh? No, I’ve grown… too…”

I started to respond, but then I realized. Even though I did grow as a dragon, my human form’s appearance hadn’t changed at all. I didn’t know if it was due to the magic or due to dragons’ longevity being so extraordinarily long, but I stayed looking like a twenty-something year old youth.

“My height hasn’t changed at all?”

“Nope.”

Nina answered me immediately. She’s seen me practically every day, so it’s probably not wrong if she says so.

“Then maybe we should base it on me…?”

If I recall correctly, I was a hundred and seventy-five centimeters tall in my previous life. I might’ve shrunk somewhat in my later years, but I remember getting to that height and staying there for ages since it was such a nice, easy-to-remember number.

“Yuuki, can you make a mark on it at my height?”

“Sure. Don’t move, okay?”

Once I stood next to a column that was supporting the cla.s.sroom’s roof, Yuuki unsheathed her sword and in a single motion leapt forward. The wind following her movement caused my hair to move slightly and I heard the sound of the wood above my head be cut.

“Now we divide this into seven… mmm, splitting it seven ways is difficult…”

You get twenty-five after dividing a hundred seventy-five by seven to make it easier to use, but splitting it up into seven was unexpectedly difficult.

“Oh, right. Violet, could you hand me a vine of about this length?”

“Certainly.”

Still not knowing what I intended and tilting her head to the side, Violet easily grew a vine from her finger and handed it to me. Once I cut it to my exact height, I made a circle and laid it onto the ground, drawing a seven-pointed star inside it.

It’s difficult to divide a line into seven, but it’s relatively easy to draw a seven-pointed star. As an occult enthusiast, I’d drawn it over and over in my previous life, after all. I never thought it’d be useful for something like this, though.

Seven is the only single-digit number that cannot divide evenly into three hundred sixty degrees. One week is seven days, there are that many holes on a face after adding together eyes, ears, nose, and mouth. It holds an importance in magic. Well, I suppose there was no meaning to it in my previous life, then.

… Come to think of it, I haven’t thought about it till now, but I wonder if magic formations would be useful for any of this world’s magic?

“What’s that?”

“It’ll be easier to get an even split if I do it like this.”

Answering Nina’s question, I cut the circle wherever the points of the star touched it and gathered the pieces up. The seven pieces of vine were all the same length.

This time, I drew a pentagram in the same fas.h.i.+on and divided one up into five centimeter lengths. I’d be able to accurately draw a pentagram if I had a mariner’s compa.s.s and a ruler, but doing it manually like this is quicker. For an occult enthusiast like me, this was the basics of the basics.

I could draw another pentagram and divide them into centimeter pieces, but the vine itself is too pliable, so that’d just increase the margin of error. It should be fine without going down to such detail for now.

“Hey hey, Mentor, what’s that~?”

Not really seeming to understand what I was doing, Rin spoke up after seeing me divide the vines up into pieces. Everyone else seemed to be just as confused, so it looked like no one got it.

“Alright. If I had ten water apples and three scarlet potatoes, which do I have more of?”

“There’d be seven extra water apples!”

Rin raised her hand and answered energetically, so I nodded in response. It was simple mathematics, but it was surprisingly hard to get her to be able to understand the comparative difference in volumes. It was the result of Nina’s steady efforts in educating her.

“Alright, now, between Violet and Nina, who is bigger?”

Rin looked from Nina to Violet and back again and placed her finger against her forehead in thought.

Then, realizing something, she pointed at Violet’s b.r.e.a.s.t.s and spoke.

“Violet’s twice as big!”

“I’ll punch you.”

Nina clenched her fist after hearing Rin’s honest response… Come to think of it, those hadn’t grown at all either….

As soon as I thought that, Nina swung at my head.

… Seriously, ow.

“Not that… their height. Even if you understand that Violet is taller, you’d be stumped to answer by how much right?”

“About this much—wouldn’t work, then?”

s.h.i.+g showed their height difference with his hands.

“Oh! So you mean to give a name to that feeling of about this much?”

“Yeah, exactly!”

I responded emphatically, practically clapping.

“Just like how you can count how many nuts there are or how many objects or animals there are, you can enumerate the length of something with a centimeter. Each of these small vines are five centimeters. For example, my height becomes a hundred and seventy-five centimeters.”

“Hundred… seventy-five…”

Rin hadn’t had to deal with such large numbers usually, so she repeated it over again to try and wrap her head around it.

“Hey. How about me?”

The first person to ask that was s.h.i.+g.

“Violet, could you give me another vine?”

“Sure. One moment, please.”

Violet picked up one of the twenty-five centimeter vines I cut and, concentrating, closed her eyes with it in her hand. Following that, she moved the vine in her hand around a few times while slowly producing another from her hand.

“Will this be fine?”

“That’s amazing!”

I exclaimed upon seeing the vine she produced. The vine Violet made had a thorn every twenty-five centimeters along it. It was very convenient. It also consequently showed that she understand the concept of unit lengths.

“Alright, then stand in front of the column. Let’s see…”

After making a mark on the column to match s.h.i.+g’s height, I measured the mark’s height from the ground with the vine I got from Violet. It was just a little higher than the fifth thorn, and was practically just right after adding a five centimeter vine.

“s.h.i.+g, I’d say you are around a hundred and thirty centimeters tall.

“Big brother, measure me too!”

“What about me? What about me?”

“I’d like to know too.”

Everyone seemed like they wanted to know their heights and started to speak up, so we suddenly ended up having our first body measurement session.

Nina was a hundred and fifty-five centimeters tall. Violet was just a little shy of a hundred seventy. I was a bit confused about where exactly I should measure to on Luka, but the height to her head from her standing upright as she normally did was a hundred and sixty centimeters. Rin was about a hundred centimeters when I measured her the same way, but she was a hundred and seventy when I measured the full length of her body from head to tail.

“Yuuki is… a hundred and thirty, I’d say.”

“Eh, the same as me!?”

When it was finally Yuuki’s turn, s.h.i.+g was surprised.

“Oh, pretty much.”

Yuuki waved her hand above her and s.h.i.+g’s head as they stood back-to-back. Five years ago when they first met, s.h.i.+g was a good bit taller.

“Yuuki, how old are you now?”

“I’m fifteen years old!”

It’s already been that long? She has grown a lot, both in her height and that her former boyish body has gotten more feminine.

“These got bigger too~”

“Yep. They have.”

Yuuki answered Rin, not seeming to mind the fact that her b.r.e.a.s.t.s were latched onto by Rin in an eagle grip.

I guess the reason I didn’t feel like she’d grown up much was because of her ever-present childish personality. Her climbing my body like some monkey’s never stopped, after all.

“Stop that, it’s shameless.”

I rebuked her out of habit, but I appeared to be the only one embarra.s.sed among the mostly female group here. Even though s.h.i.+g was also a man, lizardmen females didn’t develop b.r.e.a.s.t.s, so he didn’t have that same feeling about them.

“It’d be nice to get our weights too.”

“Exercising~?”

“I mean figuring out how much we weigh.”

Rin tilted her head and I answered her.

Even though I said that, measuring weight is much more difficult than height. How should I go about making a scale?

I couldn’t even consider it, honestly. Draw water and measure it with a balance? I don’t even really know how to make the scales though.

“Weight has a number too?”

“Yeah. Most things can be represented by numbers.”

“Then… magic, too?”

Hearing Rin, my breath caught. It’s true, magical strength comes in all sorts, but I’ve never even thought of how to go about representing it numerically.

After all, magic’s strength varies way too greatly depending on the person that uses it. I don’t think it’d be possible to measure it with a single standard like height… wait.

“Maybe so.”

Coming up with a certain idea, I spoke.

If I can’t measure it with a single standard, why don’t I just use multiple?