Reincarnated as the third son of the Duke

One hour passed.

And yet, he was still running.

The rhythmic sound of his footsteps echoed across the training grounds.

He neither gasped for breath nor slowed his stride.

Aizen watched with wide eyes, his expression one of disbelief.

But the most surprised person on the field was William himself.

"What the hell? Why am I not tired?"

By all logic, he should have collapsed by now.

Even if he didn't fall, his legs should have grown sluggish, his breath ragged.

That was how the human body functioned—at least for those who hadn't transcended their limits.

Yet, strangely enough, his body showed no signs of fatigue.

"Young Master, are you truly all right?" Aizen finally asked.

William, still running, responded with an equally confused look.

"For some reason... I seem to be fine."

Another thirty minutes passed.

And still, he showed no signs of exhaustion.

Eventually, Aizen let out a dry chuckle, realizing the futility of continuing the exercise.

"It seems this test serves no further purpose. Come here for a moment, Your Highness."

William slowed to a stop and approached.

Aizen took hold of his wrist and pressed two fingers against the faint blue veins beneath his skin.

"I will examine your physical state. You may feel something unusual, but do not move."

As soon as William nodded, a cool sensation seeped into his wrist, spreading through his body.

A faint tremor ran through him at the unfamiliar feeling.

"Is he using his magic to sense the internal structure of my body?"

William couldn't help but admire the technique.

Magic was notoriously difficult to manipulate without manifesting it externally.

Yet Aizen was delicately guiding his magic through William's body, probing every part with the precision of a master craftsman.

There was no pain, only the slightest discomfort—likely the result of Aizen adjusting the magic's properties to harmonize with William's own energy.

This level of control was beyond what William had ever imagined possible.

At last, Aizen's eyes trembled, his expression shifting through a whirlwind of emotions.

Disbelief. Excitement. Regret. Relief. Contemplation.

And something else William couldn't quite place.

After a long pause, Aizen withdrew his magic and fixed William with a piercing gaze.

"Your Highness, I must ask you something. Have you practiced energy circulation on your own recently?"

"Yes," William answered without hesitation.

There was no reason to lie.

The previous owner of this body had already been taught basic energy circulation, and it was common knowledge that external guidance made learning it far easier.

Aizen, seemingly expecting that response, nodded.

But his next question carried a far heavier weight.

"Have you ever felt any obstruction, pressure, or pain while circulating your energy?"

William tilted his head slightly.

"No, I haven't."

"...Not even the slightest resistance?"

"None. It flows smoothly, like a waterwheel in motion."

"...Hah. Hahaha. Hahahaha!"

Aizen threw his head back and laughed.

His face contorted through a chaotic mix of emotions, making it impossible to tell if he was joyous or deeply troubled.

William couldn't fully grasp what was going through Aizen's mind, but he had a rough idea of what the Sword Saint had just discovered.

"He must have realized that my pathways are already fully opened."

Thinking back, his endless stamina earlier likely had something to do with his unique physical condition.

While William lacked the knowledge to fully comprehend the implications, Aizen was one of the strongest swordsmen in history.

If anyone could discern the true extent of his body's potential, it was him.

"I'd like to ask him outright… but that would be suspicious."

A third prince who had never even mastered a proper sword technique suddenly asking complex questions about energy circulation?

That would raise unnecessary doubts.

It was better to wait until Aizen decided to reveal the truth on his own.

After several moments of silent contemplation, Aizen let out a deep sigh.

"I understand now."

"Is there something unusual about my body?"

Aizen smiled faintly.

"Quite the opposite. Your body is more suited for the Lionheart Sword than anyone I've ever seen."

"...I beg your pardon?"

William blinked in confusion.

"Your Highness," Aizen's expression grew serious, his voice steady and deliberate.

"Instead of vying for the position of House Hern's successor... have you ever considered aiming to become the next Sword Saint?"

"...!?"

William was too stunned to respond.

Abandon the struggle for succession… and instead pursue the path of a Sword Saint?

Seeing his confusion, Aizen spoke again, his tone calm and measured.

"Your Highness, you may have dismissed the ease of your energy circulation as insignificant, but in truth, it is an extraordinary blessing."

Energy circulation was the process by which the body purified itself, gradually clearing blockages in the internal pathways.

Even if practiced daily without fail, the process was incredibly slow.

For a child who began training early, achieving full circulation typically required decades—at best, a lifetime of dedication.

And that was assuming the individual also practiced advanced sword techniques to refine their energy.

Neglect even a single step, and the pathways would remain obstructed for an entire lifetime.

"But Your Highness…" Aizen exhaled slowly, as if trying to contain his own astonishment.

"You were born with all your pathways completely open."

William stiffened.

"...Meaning?"

"Meaning you have surpassed what others take a lifetime to achieve, before even beginning formal training."

"...Then I am simply ahead by a few decades, am I not?"

Aizen shook his head.

"It is far more than that."

William frowned.

"What could be greater than such a head start?"

Aizen's voice trembled slightly as he spoke the next words.

"If all your pathways had been open from birth, then your body has already undergone complete purification. There is no higher state."

William's breath caught in his throat.

Then…

"And yet," Aizen continued, his gaze burning with an intensity William had never seen before, "your body is still refining itself. Even now, however faintly, your circulation continues to improve."

William's mind reeled at the implication.

It meant one thing.

His body had already reached perfection.

Yet somehow—he could still grow stronger.