It was just another ordinary day, like always.

Kurato, as usual, had been discovered by the servants in the study and escorted back to his bed as part of the routine event.

He was just about finished reading all the worthwhile books in the study.

What remained were novels and cookbooks—fields completely different from what he was looking for.

Even so, there were two unresolved mysteries among them.

The first was a single picture book sitting among shelves full of literary works.

Its contents were nothing more than a classic hero’s tale, yet it described events Kurato had never heard of.

The outline went like this.

At one time, evil enemies descended upon a peaceful world. They destroyed cities and tormented the people who lived there. At that moment, a single young man appeared gallantly. Swinging his pure white hair, he cut down the evil enemies one after another with the sword of light in his hand. The enemies fled into the sea, but the sword of light he threw split the ocean apart and erased every last one of them. Thus, peace returned to the world.

The title of the book was Takemikazuchi.

Takemikazuchi was known as a god of lightning, a deity so powerful he was counted among the Three Great Gods.

The sword of light depicted in the picture book was likely lightning itself and lightning powerful enough to evaporate the sea would be far stronger than anything found in nature.

But that was beside the point.

What puzzled Kurato was why a picture book like this was placed on that shelf.

Was it an extremely famous picture book?

Or did it have some connection to his mother’s research?

He didn’t know.

The second thing that bothered him was that some of the books had torn-out pages.

This was especially common among books related to abilities.

Each book only had a few pages missing, but there seemed to be a pattern.

When he checked the indexes, the missing pages almost always contained the same term.

If he remembered correctly, it was called the Madeline Principle.

He didn’t know what it meant, but it was probably a principle that irritated his mother.

The torn edges were relatively fresh, so she must have been the one who ripped them out.

Perhaps it was research by scholars from a rival faction.

But that didn’t matter.

What mattered now was focusing on abilities.

While Kurato was thinking like that, he realized the escort back to his bed had already finished.

That was when he noticed something strange—something different from usual.

The bed was quiet.

That was odd.

Raito was there, which made it even stranger.

Normally, Raito was the reason Kurato’s escapes were discovered.

When Raito woke from his nap and was left alone in the bed, he would always burst into loud crying.

If Kurato or their mother was nearby, he would calm down, but if not, he would cry loudly until he exhausted himself.

A servant would then come to soothe him and notice that Kurato was missing.

These days, whenever Raito cried, the servants were so conditioned that one of them would immediately check the study first.

But that experience probably wouldn’t be very useful going forward, since Kurato planned to reduce his study break-ins anyway.

That aside—

Raito wasn’t crying.

He wasn’t asleep either.

His eyes were locked straight onto Kurato, his moist gaze desperately trying to convey something.

Was it just Kurato’s imagination, or was his complexion redder than usual?

“Aaaah!! Waaahhh!!”

A sudden siren-like cry rang out.

Raito scrunched up his face and burst into tears, stretching his small hands desperately toward Kurato.

And—his hands were very hot.

No, his whole body felt feverish.

When Kurato touched him, he was shocked by just how intense the heat was.

This wasn’t just a bad cold.

“What’s wrong, young master?”

The butler arrived.

Kurato didn’t know most of the servants’ names, but he had recently realized that this person was in charge of managing them.

“Kurato, you mustn’t bully your big brother.”

It seemed the butler thought Kurato was the culprit.

Maybe he thought Kurato had grabbed Raito’s hand and pulled him.

Kurato started to protest, then stopped.

Raito could only babble and if Kurato started speaking—even in broken words—that would cause serious problems.

Instead, Kurato placed his hand on Raito’s forehead, then placed his own hand on his own forehead and looked at the butler.

“Huh? Um… should I put my hand on him?”

The butler tilted his head, doubting his own interpretation and touched Kurato’s forehead.

Then he touched Raito’s forehead.

“Hot! W-What?! This is bad!”

Shouting for a doctor, the butler rushed out of the room.

Left alone together on the bed, Kurato took Raito’s hands again.

This was bad.

Now that he was touching him directly, Kurato could vaguely sense the magical power inside Raito.

Normally, it felt like a clear stream.

Now, it was a raging torrent, swirling violently inside him.

This must be Ability Fever.

Kurato recalled the contents of the literature.

A terrifying illness that could lead to death in the worst cases.

Raito hadn’t used his ability, but he possessed an enormous amount of magical power, so it was possible he had developed it anyway.

To cure it, one had to suppress the magical power or release it.

Releasing it was impossible.

Raito couldn’t consciously use his ability.

That meant suppression was the only option—but how?

Kurato broke out in a cold sweat as he faced the raging torrent.

He had to do something.

Raito was the one who had saved him.

Kurato took Raito’s right hand—the hand that had grabbed him and saved him “that time”—and gently wrapped it in his own palm.

First, he decided to try bringing it closer to its usual clear flow.

He sent his own magical power into Raito.

But against the torrent, it was barely effective.

‘So my magical power is basically nothing.’

Kurato thought bitterly.

No.

There was no time to be discouraged.

If pushing didn’t work, then he’d try pulling.

This time, Kurato drew Raito’s magical power into himself.

Surprisingly, the exchange happened easily.

Just as Kurato was feeling impressed and relieved—

A massive amount of magical power came rushing into him.

“Ghh… ughhh…”

Letting out a groan completely unlike a baby’s, Kurato focused with all his might to avoid being swept away.

Not that way. This way.

Flow this direction. Just flow straight.

Little by little, Kurato corrected the chaotic flow.

It nearly burst out of control, but using both his own magical power and the portion of Raito’s power he had managed to rein in, he built something like a dam inside his body.

As he did, calmer flows of magical power began to increase.

He gradually sent those back into Raito’s body.

Eventually, the raging torrent became a smooth, layered flow, circulating through both Raito and Kurato.

He returned it to Raito little by little.

Finally, after returning even the power used to form the dam, Raito’s magical power settled into a flow close to its usual clear stream.

“Aa—oo.”

Raito stared at Kurato with a surprised expression.

His complexion looked much better.

“Fevuh… gone. Good.”

Relief washed over Kurato and his consciousness suddenly began to fade.

But… had Ability Fever really been cured so easily?

Surely not.

A doctor needed to examine him—

That was as far as Kurato’s thoughts went before his consciousness fell away.

* * *

Knock, knock.

“Madam, it’s Yanagi.”

After lightly knocking, a small “Please come in” came from inside the room.

When the butler Yanagi opened the door, he saw Madam holding Raito with a face that looked ready to burst into tears.

She asked him.

“He still feels warm. What did the doctor say?”

She placed her hand on Raito’s cheek and peered anxiously at his sleeping face.

Yanagi recalled the doctor’s words.

“His magical power is already stable and his condition should return to normal soon.”

“Really?”

Madam still didn’t look convinced.

But Yanagi trusted the family doctor.

At the very least, he wasn’t someone who would lie just to offer false comfort.

Still, he understood her worry.

Ability Fever was a dangerous illness.

Sometimes it healed with rest, like influenza or mumps, but for someone like Raito—newborn and with enormous magical power—the worst outcome wouldn’t have been surprising.

And yet, he was already recovering in less than half a day.

Even adults usually needed at least three days of bed rest.

“The doctor said the disturbance in his magical power has already been corrected and since the flow is stable now, there’s no risk of recurrence.”

“Well, that means he can already control his magical power! Amazing! Just as expected of my Raito!”

Madam hugged Raito tightly in joy.

Watching from the side, Yanagi opened his mouth, then closed it.

Then, as he tried to open it again—

“Is something wrong, Aya-chan?”

Madam looked at her worriedly.

That expression wasn’t that of a mistress and servant, but of old friends.

“Makiko… no, Madam. About what happened when his fever started…”

Yanagi recalled the scene from that moment.

She had hurriedly ordered the maids to contact the doctor and Madam, told others to prepare hot water and clean towels and rushed back to Raito.

She needed to check for other symptoms.

Change his clothes.

See if he wanted water.

And Kurato was there too.

Ability Fever wasn’t contagious, but just in case, she thought Raito should be isolated.

But when she entered the room, the first thing she saw was the brothers holding hands.

Someday, Raito would surely go to a different world from both Kurato and the servants, carried away by his extraordinary talent.

But just for now, they could be close brothers.

Thinking that, Yanagi hadn’t immediately pulled Kurato away.

Then she noticed it.

Raito’s complexion looked better than before.

On the other hand, Kurato’s face was bright red, as if he were resisting something.

He had done something.

Kurato had done something to Raito that restored his condition.

Yanagi instinctively understood.

And then she noticed something else.

“Fevuh… gone. Good.”

Kurato had spoken.

He had spoken, haltingly, but clearly.

A baby who hadn’t even reached his first birthday yet.

Impossible.

Even saying “mama” or “papa” would be early at that age.

Forming full phrases was far beyond that.

You could tell her he was the reincarnation of Christ or Buddha and she might have believed it.

As Yanagi recalled that moment and spoke to Madam—

“Thank you, Yanagi.”

Madam smiled.

A smile so sad it looked as if she might cry.

“It’s fine. You don’t have to exaggerate Kurato like that. I think Kurato just gave all of his magical power to Raito. That’s the only explanation. It has to be that way. Kurato can live here as an ordinary boy. But…”

She continued.

Raito would eventually go somewhere out of reach.

The main family would never leave such a prodigy alone.

So for now, she wanted to love him with everything she had.

Until the inevitable farewell came, she wanted to give him as much love as possible.

During that time, Kurato might be made to suffer.

And so—

“Until Raito leaves and until Kurato’s turn comes… please take care of Kurato for me.”

After saying that, Madam lowered her gaze to Raito again.

Her expression looked hollow, as if she were convincing herself.

* * *

Some time passed after Raito had contracted Ability Fever.

Since that day, Kurato had noticed that his own magical power had increased slightly.

Before, he could only create three acrylic plates.

Immediately afterward, he could create eight.

Now, he could create eleven.

He reasoned that temporarily circulating such a large amount of magical power through his body had stimulated his own reserves, increasing them.

He also stopped escaping from the bed and reduced his reading, instead spending all day manipulating acrylic plates.

That led him to discover two new upgrades.

The first was control.

He could now move the acrylic plates.

Previously, once created, they stayed fixed in place and disappeared after a few minutes.

Now, though slowly, he could move them up, down, left and right.

Thanks to that, he could place plates under his hands and feet and move them, allowing movement much like riding an escalator.

In any direction he liked.

For some reason, upward movement stopped past a certain height, but in other directions, he could move them freely for dozens of seconds.

Out of curiosity, he tried lifting something heavier than himself, such as the bed.

The bed didn’t budge.

But when he lifted both Raito and himself, it lasted only twelve seconds.

The heavier the object and the higher he tried to lift it, the more magical power it consumed.

It seemed abilities followed physical laws as well.

The second discovery was synthesis.

He succeeded in creating a plate even thicker than the acrylic ones.

It was a dull, dark color, barely transparent and he decided to call it an iron shield.

He named it that because he assumed it had about that level of durability.

For now, he could only create one iron shield.

When he did, he could only create one acrylic plate.

It seemed that one iron shield required the same magical power as ten acrylic plates.

Of course, the iron shield could also be moved.

Its size was the same as an acrylic plate, so it couldn’t carry much on its own.

But Kurato felt his magical power increasing day by day.

Someday, if he could create more of these shields and strengthen them further, he would be able to fight again like he once had.

Kurato thought back to the version of himself that had fought in another world.

More precisely, to a part of the abilities he had used then.

A massive tower shield large enough to conceal his entire body.

Small shields that automatically reacted to hostility.

Only when he could do things like that would his ability become a truly combat-capable power.

For now, Kurato resolved to train his ability with that as his goal.

“…Hm?”

Again.

That feeling of being watched.

This sensation had started after he saved Raito from Ability Fever.

He considered that someone might actually be watching him, but there was no presence.

He was still a baby, so it wasn’t as though he had the perception abilities he once did.

Maybe he simply couldn’t detect it.

Still, it began without any sound and ended just as suddenly.

If someone were nearby, there should have been some noise.

Unless they were an incredibly skilled assassin…

“…Well, whatever.”

There was no point worrying about it.

There didn’t seem to be any killing intent.

And even if there was, he couldn’t do anything about it right now.

So he ignored it.

Or perhaps, resigned himself to it.

* * *

Yanagi stood perfectly still in the freshly cleaned room, her eyes closed.

She wasn’t asleep on her feet.

She was watching.

Today as well, Lord Kurato escaped from the bed and is practicing his ability. Transparent plates… likely a create-shield type ability. He’s riding them and moving around the room.

He’s faster than when I watched before and his movements are smoother. Lord Raito is watching and cheering happily. How heartwarming.

Ah—Lord Raito is trying to stand and almost falling… Lord Kurato caught him. With a shield, no less. Can a creation-type ability really do that? With levitation, perhaps, but creation abilities usually require wielding the created weapon directly.

Oh? Lord Kurato is speaking to Lord Raito. What is he saying?

“Careful?” “Don’t stand up?”

He seems to be warning him.

Lord Kurato is already conversing normally. It’s wonderful that I can understand him just by reading his lips.

But… can a one-year-old speak this fluently? No. Impossible.

Lord Raito only just managed to say ‘mama,’ and Madam nearly lost her mind with joy. That’s normal.

Lord Kurato truly is extraordinary.

Normally, abilities only manifest in elementary school.

Even at the earliest, glimpses of power appear around age three.

And yet…

Yanagi opened her eyes and sat down in a nearby chair.

If only Madam would see this directly, perhaps her interest in Lord Kurato would grow even a little.

But she refuses to look.

She fled this house after severing ties with that man and he remains missing.

Because Lord Raito possesses extraordinary ability, his treatment changed, but because Lord Kurato is only E-rank, she can’t even bring herself to face him.

It’s as if she believes that as long as Kurato is here, that man will never return…

Yanagi closed her eyes again.

Oh, now he’s standing on the floor… dancing? He’s flailing his limbs while floating shields around him. How adorable. Lord Raito is so excited too.

Such joyful brothers.

If only it could stay like this forever…

A single tear quietly slipped from Yanagi’s closed eyes.

* * *

“Akya! Akya!”

“Raito, no. This isn’t play. This is body training. Watch closely… there!”

“Nii-ni! Nii-ni!”

“Hey, Raito. Don’t stand up again. Sit properly.”

“Akya!”

Unaware of Yanagi’s feelings, Kurato continued to train steadily.

* * *

Memo

The Madeline Principle ← a suspicious rule the mother is hiding.

The protagonist’s magic power increased. Acrylic Plates: 3 sheets → 11 sheets.

He became able to move Acrylic Plates (very slowly).

He became able to create Iron Shields, the superior form of Acrylic Plates (10 Acrylic Plates = 1 Iron Shield).

The father is missing? ← requires caution.