Gluttony Demon King with the Swampman ~A Man with No Magic Power Who Dreamed of Magic, Wielding Knowledge from His Past Life Through Steady Research and Hard Work to Become the Most Vicious Final Boss~ - Chapter 12: The Mirror Image Hypothesis

Chapter 12: The Mirror Image Hypothesis

Mirror-image isomers.

They are shapes that can never overlap.

Take a hand as an example.

If you imagine a left hand and a right hand—two objects made of exactly the same material—no matter how you rotate them, the left hand and the right hand will never match up perfectly.

The only way to make a left hand overlap with a right hand is to flip one of them in a mirror.

When you hold your left hand up to a mirror, the reflection looks exactly like a right hand. That reflected shape can now overlap with a real right hand.

The same substance, yet they don’t overlap—only when one is mirrored do they become identical. This three-dimensional relationship is called “mirror-image isomers.”

The idea mostly comes up in organic chemistry.

A famous example is glutamic acid.

That’s the stuff in MSG, the main flavor component in kombu broth.

Glutamic acid actually comes in a left-handed form and a right-handed form—mirror-image isomers of each other.

Here’s the interesting part: the left-handed version gives the rich umami taste on your tongue, while the right-handed version tastes like absolutely nothing.

In short, the “direction” a molecule faces can change everything.

That’s probably the true nature of the mirror twins’ curse.

Mirror twins are born with certain body features flipped: dominant hand, the swirl of their hair part, the position of internal organs—everything mirrored.

It seems likely that even the shape of the magical power they produce is reversed between them.

“Let’s call it Mirror-Image Magical Interference,” I said.

Their mirrored magical energies are interfering with each other.
That’s my hypothesis.

“Wh-what are we supposed to do!?” Zaria cried.

“In this case the solution is simple,” I answered. “One of you just needs to flip your magical power to match the other’s orientation.”

“…How?”

“You already have the perfect tool for it.”

I pointed to the black leather pouch hanging at Noiche’s waist.
The sisters looked at each other.

“The celestial telescope…!”

They shouted the answer together and hurriedly pulled it out, tossing it to me.

“Correct. A reflector made of flume spirit silver. That liquid metal reflects not only light but magical power as well. And reflection means ‘to flip like a mirror image.’”

As I explained, I snapped the telescope cleanly in two.

Both girls flinched, shoulders jumping, but they said nothing and simply watched me work.

“Bakegujira Ink.”

In response to my chant, the ink rippled like it had been squashed, then began drawing a magic circle all on its own.

Bakegujira Ink—the very first original spell I ever created.

Its effect is this: when another liquid is poured into the ink, the ink does not digest and absorb it as food. Instead it keeps the liquid’s properties unchanged while merging it into its own body.

Normally a slime digests everything that enters it without exception, but this spell stops that digestion process.

The foreign substance keeps its original nature while becoming part of the ink’s flesh.

That lets me grant the ink all kinds of chemical properties and watch what happens—basically an experimental spell.

Today it was going to save us.

I tilted the broken telescope. Silver liquid metal poured out with a steady tok-tok-tok and flowed into the ink.

The ink swallowed every drop, mixing it in.

A faint metallic sheen appeared across its smooth, inky body.

Flume spirit silver—the magical metal that acts as a perfect mirror even to magical power.
I lifted a portion of the newly enhanced ink onto my fingertip.

“If we fire your magical energy against this ink, it will flip your power into its mirror image. However,” I warned, “that also means everything you’ve trained for over the past ten-plus years—the muscle memory of controlling your magic—will suddenly feel completely foreign. You’ll have to relearn it from scratch.”

Relearning a lifetime of spellcraft in the next few minutes.

The effort alone would be brutal, but the real problem was that we needed combat-ready mastery right here, right now, before that ice dragon killed us all.

“Who’s going to do it?”

Noiche raised her hand without hesitation.

“I will.”

“…You sure you can handle it?”

“I’ve always left the hardest parts to Zaria. This time it’s my turn.”

And besides, I’m good at surprising the teacher—she smiled as she said it.

“Zaria, will you help me?”

“O-of course!”

Good. That settles it.

I nodded and split the ink in two.

I left half floating above Noiche’s palm and took the other half with me as a weapon.

The ice dragon, raging in blind fury, finally noticed we had moved far away.
Its silver eyes glared at us, ready to charge at any moment.

If I left it alone, Noiche wouldn’t be able to concentrate on reconstructing her magic.

Zaria needed rest—her shoulder wound was worrying me.

So I would buy them time alone.

“Bounce Seal: Pinball.”

A magic circle bloomed beneath my feet.

I kicked off the ground and launched myself forward.

The dragon roared and spewed freezing mist.

“Chain Crown: Chainsaw.”

The ink that followed became my blade.

I rolled under the sweeping tail, swung the ink at the same moment, and slashed the glowing dawn-colored weak points marked along its body.

“Still rock-hard as ever…!”

I shattered the outer shell of ice armor.

But the dragon scales beneath were still ridiculously tough.

I leaped over ice spears erupting from the ground, then kicked off mid-air bounce seals to dodge sideways through a barrage of ice bullets and snapping jaws.

All I had to do was buy time.

I didn’t need to kill it—just keep hitting the weak spots so it never turned toward the sisters.

I memorized its attack patterns.

Downward claw swipe.

Tail sweep.

Breath.

Ice bullets.

“Swirl back.”

I caught the bullet curtain with ink chains and neutralized it.

Tail sweep, charge, bite—I evaded everything, and right after, the dragon took to the sky.

Sniper ice bullets from above.

I dodged whatever I could without wasting ink.

Ice spears raced across the ground after me.

“Bounce Seal: Pinball.”

I escaped upward into the air, kicked off airborne seals, closed in fast for a counterattack, then immediately pulled back to prepare for the next strike.

Every single attack was instantly lethal if it connected. My heart never slowed, yet somehow I felt eerily calm.

Then a wind blew.

A cold that crawled over my torn skin—not a howling storm, but a swirling vortex sucking everything toward the dragon.

I knew instantly: the prelude to that monstrous freezing explosion.
Yet—

“You’re too late. They’re already finished.”

There was no fear.

Because across the battlefield our eyes met.

Strands of hair whipped in the wind.

Noiche held the ink above her open palm, and Zaria hugged her little sister tightly from behind, eyes gently narrowed.

Incantation.

The sisters wove their ritual words in perfect alternation.

“Rising fire whale”

“Silent calm great owl”

“Dawn”

“Reverse cup”

“Awakening lark”

“Crossing to journey’s end”

“We are those who guide the blazing light”

“We are those born from the progenitor of night”

“Tear the dark sky—Kiraboshi!”

The moment their voices overlapped—the spell was complete.

From Noiche’s palm burst a night-black flash entwined with twisting rose-colored rings of light.
Blue and red spiraled together, reached the target in the blink of an eye, and—

punched straight through the glowing red throat of the dragon as if it were paper.