Chapter 18: After School Guidance

According to Unohana's earlier explanation of Kaido, it was a technique designed to repair spiritual bodies by manipulating reishi. But Ren wasn't a spiritual entity—he was flesh and blood. When he first learned of the principles behind Kaido, he had assumed the skill would be useless to him.

Yet, Unohana had successfully healed his wound. This forced him to rethink: What exactly was the distinction between a physical body and a high-density spiritual body in this world?

Drawing from basic scientific knowledge from his past life, Ren wondered—could reishi simply be another form of matter, like molecules or atoms?

Of course, there was also the possibility that the 'disguise' provided by the EndSpace was so flawless that it temporarily allowed him to function as if he possessed spiritual properties.

As the lesson progressed, each student was given a small white mouse to practice Kaido. After all, not everyone could successfully perform the technique; relying on self-inflicted wounds during practice would likely leave the majority needing Unohana's help to heal themselves.

Ren made a small cut on his mouse and began his attempts, trying to recreate the sensations he'd experienced during Unohana's demonstration.

Kaido proved to be far more challenging than it appeared. His first attempt failed.

Then his second.

And his third.

It wasn't until his fifteenth attempt that he managed to grasp the technique, controlling the reishi to repair the mouse's injury.

A short while later, the mouse's wound had healed, though it left behind a noticeable scar.

Clearly, Ren's proficiency was far below Unohana's. Not only was his speed of healing slow, but the results were also far from perfect.

"You need to focus on visualizing the original, uninjured state and then guide the reishi to restore it," Unohana said softly, her breath faintly tickling his ears.

 At some point, she had moved to his side, silently observing him with a strange glint in her eyes.

When she glanced at the mouse on Ren's desk, a flicker of surprise crossed her usually composed features. In all her years of substituting for this class, she had never seen a student successfully perform Kaido during their first lesson.

By the standards of the Shin'ō Academy, Ren had already achieved a passing grade in Kaido. With further practice, he could easily become a qualified medical officer in Squad Four.

Could this child truly have no weaknesses?

She had heard rumours that Ren had already left his Zanjutsu and Hakuda instructors at a loss. Those two instructors, in private, had confessed that they were simply "unable to teach him."

It wasn't a criticism of his personality or demeanour—it was simply that he was beyond their ability to instruct.

At this moment, Unohana was quietly grateful for her unparalleled expertise in Kaido. At least in this domain, she could still teach Ren.

Under Unohana's guidance, Ren made another incision on the mouse. This time, as he applied Kaido, the wound healed more quickly, and the scarring was far less noticeable.

Unohana's eyes lit up, and she leaned in even closer, staring into Ren's eyes. "Let me ask you, why are you so eager to learn Kaido?"

Deep in concentration, Ren responded instinctively, "Of course, it's to better enjoy combat."

As soon as the words left his mouth, he felt a shift in the atmosphere. A palpable pressure enveloped him, and when he looked up, Unohana's eyes gleamed with a thinly veiled excitement.

'I fucked up-'

Ren immediately regretted his honesty. He shouldn't have revealed his true intentions.

How could he have forgotten?

Unohana was a battle maniac herself. She had only relinquished her role as Captain of Squad Eleven after meeting Zaraki Kenpachi, transferring to Squad Four to take on a supportive role.

But deep down, her thirst for combat had never waned. Her gentle demeanour was merely a carefully maintained façade.

Unohana, once known as the most dangerous criminal in the history of Soul Society, had only tempered her bloodlust after joining the Gotei 13 under Yamamoto's command.

"I see… Stay after class," Unohana said, her excitement skillfully masked by her usual gentle smile. "Since you're so enthusiastic about Kaido, I'll give you some special guidance."

Ren's spine tingled with unease, though he recognized the immense value of learning Kaido directly from Unohana. It was an opportunity he couldn't refuse.

Surely she wouldn't kill me during a medical training session…right?

On a different line of thought, Ren wondered where Kenpachi Zaraki had gone.

He had once asked his ever-trusted Aizen-pedia, but was disappointed to learn that the current captain of the 11th Division was Kuruyashiki Kenpachi.

Moreover, there was no one named Kenpachi Zaraki in the Shin'ō Academy.

As the class concluded and the bell rang, most students left the room with disappointment etched on their faces, unable to successfully heal their mice. Ren, however, had no other classes scheduled that afternoon.

When the last student exited, a faint spiritual pressure stirred the air, and the classroom door swung shut.

Ren's sharp hearing caught the distinct click of a lock.

He looked up at Unohana, who still wore her soft, graceful smile. Her pale hand rested lightly on the hilt of her zanpakutō.

"Ren-kun, it's just the two of us now~"

Her delicate fingers wrapped around the hilt of Minazuki. Slowly, she began to draw the blade, inch by inch.

"Unohana-sensei?" Ren asked cautiously, alarm bells ringing like crazy in his mind. "What are you doing?"

Unohana's warm smile never wavered. "Naturally, I'm going to let you experience advanced Kaido firsthand."

Before Ren could raise a hand to protest, a crimson geyser erupted, painting the ceiling red.

The afternoon lights seeping through the window dyed the room an eerie red, matching the pooling blood under Ren's feet.

The delayed pain forced his brain to realise what was happening, and what followed after the sharp pain was uncontrollable excitement.

This… this is incredible!

Ren wasn't a masochist, but it was the first time he'd encountered a blade so fast, so precise, that even his enhanced perception couldn't anticipate it.

That single strike had been utterly beyond him.

The blade had cut diagonally downward from his left shoulder, slicing through flesh, bone, and even his heart. His heart, like an old, sputtering engine, struggled desperately to keep the battered body alive. But no matter how valiantly it tried, all it could accomplish was to make the fountain of blood surge even higher.

As his bodily functions began to shut down, Ren felt himself slowly falling backwards. Yet, before he could hit the ground, a gentle hand caught him mid-fall.

Through the fading clarity of his vision, he saw Unohana's warm, sisterly smile. "I'll use your body to teach you," she said softly.

Ren gave the faintest nod. Even though he was on the verge of death, there was no panic in his eyes. He perfectly understood what Unohana intended to do: she was going to make him experience firsthand how advanced Kaido could heal even life-threatening injuries.

Mustering his remaining strength, he forced his mind to focus, determined to observe every detail of her technique.

Her hands glowed again, this time with a radiant pale blue light, far brighter and more expansive than what she had demonstrated during the lesson.

Strangely, though his body was failing, Ren found that his mind was exceptionally clear. His senses felt heightened, his awareness sharper than ever before.

Even with his eyes closed, he could vividly sense the intricacies of Unohana's Kaido. It was as though countless delicate threads were weaving through his chest, repairing the devastation with an almost otherworldly precision.

Each motion of hers seemed deliberate, practised, and impossibly refined. The sensation wasn't just one of healing—it was as if his body was being remade, thread by thread, into its optimal form.