Even Rias found herself unable to understand what Izumi was thinking.
Using a weapon powerful enough to threaten even the highest beings as enhancement material?
It was simply absurd.
Yet after a moment's thought, she could only shake her head and laugh.
That was exactly the sort of thing Izumi would do.
To him, a powerful weapon was merely a tool.
If it could be used to strengthen someone important to him, then its value increased far beyond what it could accomplish as a weapon alone.
Her gaze drifted toward the distant presence of Est.
A faint smile appeared on her lips.
"How impressive."
"That's one incredible investment."
"If the Single-Digit system didn't have its restrictions, that girl might have broken through already."
"What a shame..."
A trace of regret appeared in her eyes.
Once Est completely fused with that sword, reaching the Double-Digit realm was practically guaranteed.
Under normal circumstances, she might have even stepped into the realm of the Single-Digits.
Perhaps she could have become something akin to the Origin of Swords itself.
Unfortunately, reality wasn't that simple.
The positions within the Single-Digit realm were fixed.
Unless one of those seats became vacant, no one else could ascend.
Countless powerful beings had become trapped at the Double-Digit level because of this absolute limitation.
Even Rias had witnessed many such cases throughout the ages.
After a moment, she stopped dwelling on it.
Perhaps this was simply fate.
Meanwhile, Izumi naturally understood these rules.
He simply didn't care.
His goal wasn't to force Est into becoming a Single-Digit existence.
He merely wanted her to become stronger.
As for the future...
That could wait.
Maybe by the time they reached that stage, he would have discovered another path entirely.
After all, nobody could predict what the future held.
With that mindset, Izumi continued the fusion process.
The nameless sword steadily dissolved.
Its immense power flowed into Est little by little.
As the fusion progressed, the aura surrounding her became increasingly terrifying.
Sharper.
Deeper.
More absolute.
It felt as though the concept of "Sword" itself was evolving.
...
Down below, within Dimension City, countless swordsmen felt their scalps go numb.
Every sword user experienced the same sensation.
It was as if a legendary Sword of Damocles hung directly above their heads.
An invisible pressure descended upon them.
Their weapons trembled constantly.
Some swords even emitted faint cries of submission.
The feeling was unbearable.
Many people quickly retreated from the area, unable to endure the overwhelming sword intent.
Even powerful beings felt instinctive fear.
...
At the same time, many of Izumi's companions noticed the abnormal phenomenon.
Shiroyasha and the others looked toward the summit of the Sephiroth Tree with curiosity.
"What exactly is that idiot doing now?"
The pressure radiating from above was terrifying.
Yet none of them attempted to interfere.
After all, very few people could casually enter Izumi's private territory.
Even the girls closest to him merely exchanged puzzled glances.
They remembered seeing him leave with Est not long before the phenomenon began.
Naturally, they guessed the two events were connected.
Although they were curious, nobody rushed over to investigate.
They knew Izumi well.
When everything was finished, he would explain it himself.
There was no need to interrupt him now.
...
And so the days passed.
One day.
Then two.
Then three.
For three consecutive days, the terrifying sword aura continued to grow stronger.
The pressure spread throughout countless worlds connected to Izumi's domain.
Each day felt more frightening than the last.
Many people became increasingly convinced that some unprecedented existence was being born.
Then—
On the third day.
The oppressive aura suddenly vanished.
The pressure that had weighed upon countless worlds disappeared without warning.
Silence returned.
The fusion was complete.
At the summit of the Sephiroth Tree, Est slowly opened her eyes.
She had already returned to her human form.
Looking down at her hands, she carefully felt the power flowing through her body.
Then her eyes widened in disbelief.
"So strong..."
"I'm unbelievably strong now."
Even she was stunned by her own transformation.
She had expected to become stronger after absorbing the sword.
But this result far exceeded her expectations.
The increase was so enormous that it felt unreal.
It was almost frightening.
Seeing her reaction, Izumi chuckled and gently rubbed her head.
"That's perfectly normal."
"You've gained too much power at once."
"The next step is getting used to it."
"If you don't familiarize yourself with your new strength, controlling it will become difficult."
Est nodded seriously.
"I understand."
She knew he was right.
Power without control was meaningless.
Before she could fully utilize her new abilities, she needed to adapt to them first.
After responding, her body began glowing with soft light.
The next moment, she transformed into a stream of brilliance and returned to the Spirit Crest engraved on Izumi's right hand.
The familiar emblem shone briefly before fading.
Within the crest, Est entered another deep slumber.
This time, however, it wasn't due to exhaustion.
She was digesting her newly acquired power.
When she awakened again—
The strongest Sword Spirit in existence would emerge.
And even Izumi found himself looking forward to that day.