Unohana said nothing more. She turned around and began walking down the mountain. After a few paces, she suddenly came to a halt.
"Ren."
"What is it, Captain?"
"From now on, we cannot practice our swordsmanship here."
Ren blanked for a moment. "Why?"
Unohana did not turn around. "Just as you said earlier, if I release any more of my Spiritual Pressure, it will draw unwanted attention. This place is too close to the barracks to truly unleash it."
Ren fell silent. He knew Unohana was right. As a captain with a thousand years of experience, if Unohana were to fight with everything she had, let alone the Fourth Division, the entire Seireitei would likely detect her presence.
Ren pondered for a moment, and a certain location came to mind. "If you wish to change locations, Captain, I actually know of a spot."
Unohana turned back to face him.
"Beneath the Sokyoku Hill, there is a subterranean cavern. It's surrounded by a barrier that completely isolates Spiritual Pressure, making it perfectly hidden."
Unohana's eyes gleamed slightly. "There is such a place beneath the Sokyoku?"
"Yes."
Unohana nodded, choosing not to pry further. "Very well. Let's go take a look."
The next day, at the Sokyoku Hill.
Ren led Unohana through the hidden passageway, entering the underground cavern. The cavern was massive, easily the size of several football fields, with numerous training scars scored into the surrounding rock walls.
Unohana stood at the entrance, her gaze sweeping across the entire expanse. A flash of surprise crossed her eyes. "This really is... unexpected."
Ren walked to the center of the cavern and turned around. "Third Seat Urahara mentioned that the rock walls here have been specially reinforced to withstand high-intensity shockwaves of Spiritual Pressure. The surrounding barriers also mask any spiritual detection, so no one will notice."
Unohana nodded, her gaze then landing on the experimental equipment sitting in the corner. A few instruments, some glassware, and notebooks were scattered all over the place. A look of contemplation flickered in her eyes, though she didn't ask further.
"Are you and Kisuke Urahara close?"
Ren did not hide it. "Yes, he has helped me quite a bit."
Unohana nodded, saying nothing more. She stepped into the center of the cavern and drew her Zanpakuto. The moonlight spilled over the blade, casting a cold, crisp gleam.
"This place truly is excellent." She turned around to face Ren. "From now on, we will practice our swordsmanship here. In fact, why don't we have a round right now?"
Unohana turned, the look in her eyes completely changing as she gazed at Ren. It was no longer her usual gentleness, but a look of raw anticipation that Ren had never seen before.
"Ren, you have improved a great deal in places where I cannot see." Her voice was very soft, yet every word cut clearly into Ren's ears. "Swordsmanship, Kido, Spiritual Pressure... everything you are hiding, show it to me today."
Ren's pupils contracted slightly.
Unohana raised her blade, pointing the tip directly at him. "Our last bout didn't satisfy me. To be frank, I can tell you're holding back. You still have many things you haven't shown me. Today, if you don't fight with the intent to kill me, you had better worry about whether you can walk out of here in one piece."
The corners of her mouth curled upward into a smile Ren had never witnessed before.
Ren swallowed hard. He could feel that the Unohana standing before him was entirely different from her usual self. A nearly tangible wave of Spiritual Pressure radiated from her body, carrying a long-suppressed excitement.
"Show me your true strength."
Ren tightened his grip on his hilt and took a deep breath. He wasn't surprised that Unohana could sense what he was hiding. He also wanted to know exactly how long he could hold out against her.
Softly chanting the release phrase, his Zanpakuto instantly achieved Shikai. Ren could even feel Garenge humming with excitement in his hand.
"Captain," he spoke, his voice steady. "Please guide me."
Unohana smiled, a flash that vanished in an instant. Then, her figure vanished.
Before Ren could even react, her blade was already in front of him. He instinctively raised his sword to block, but a monumental force surged through the blade, blasting him backward. Flipping in midair, he managed to land, his feet plowing two deep trenches into the ground.
"Is this your limit?" Unohana's voice floated over from ahead, calm but carrying a trace of disappointment.
Ren raised his head. She stood exactly where she had been, not having moved a single step. That strike just now had been a mere casual swing.
He grit his teeth and flared his Spiritual Pressure. His wounds healed at a pace visible to the naked eye. This was Kaido—he was healing himself.
"Of course not."
His figure vanished from the spot. This time, he didn't hold anything back.
Pushing his Flash Step to its absolute limit, his silhouette left behind several afterimages within the cavern. Flashes of his blade slashed at Unohana from various angles, each strike laced with fierce Spiritual Pressure.
Unohana didn't retreat. Her blade traced an arc through the air, effortlessly deflecting all of Ren's onslaughts.
Ren used Flash Step to appear behind her, slashing down. Without even turning around, Unohana swung her sword backward, precisely blocking his attack.
"You are still far from it." With a twist of her wrist, a massive force transmitted through the steel, forcing Ren back several paces.
He didn't stop. The moment he landed, he raised his left hand.
"Raikouhou." Incantationless.
A burst of lightning erupted from his palm, blasting directly toward Unohana's face. Unohana tilted her head to evade. The lightning grazed past her cheek, blasting a deep crater into the rock wall.
Before she could even turn back, Ren's second Kido spell arrived.
"Soukatsui."
Pale blue flames erupted from his right hand, sealing off Unohana's paths of retreat. She tapped her foot lightly and leapt upward, evading the spreading flames.
But this was exactly the moment Ren had been waiting for.
"Kurohitsugi."
A small black cube materialized above her head and violently snapped shut over her.
Unohana's pupils narrowed slightly. Swinging her Zanpakuto upward, she sliced the Black Coffin cleanly in half with a single strike. Fragments of Spiritual Pressure scattered in all directions, glittering with an eerie light inside the cavern.
She touched down and looked at Ren. "Interesting."
A trace of praise crept into her tone as she raised her blade. This time, she gave Ren no further room to breathe.
Her figure vanished once more, her speed so overwhelming that Ren could only block entirely on instinct. Blow after blow rained down. Ren was driven back repeatedly, his arms growing intensely numb.
His Spiritual Pressure was draining rapidly. With Garenge's amplification, he was constantly using Kaido to patch his wounds, Kido to output attacks, and Flash Step to continuously evade. Under such high-intensity exertion, he could feel his spiritual energy rapidly bottoming out.
But he couldn't stop. Because the moment he stopped, Unohana's blade would cleave him down.
The chilling flash of her blade, like a scythe from hell carrying world-ending killing intent, slashed toward Ren. The fangs of the thousand-year Kenpachi were finally laid bare in their entirety.
The moment the two Zanpakuto clashed, his blade involuntarily slipped half an inch wide. Unohana's blade slid right through the gap, aiming straight for his chest.
He retreated violently, barely dodging it. His Shihakusho was sliced open at the chest, leaving a shallow, bloody track on his skin.
"Is the true extent of what you're hiding merely at this level?"
Ren stared down at the wound on his chest and remained silent for a brief moment. Then, he lifted his gaze and smiled.
"Captain, brace yourself."
In the next instant, a tempestuous surge of Spiritual Pressure erupted from the depths of his soul. The dark crimson spiritual energy condensed over his face, ultimately solidifying into a bone mask adorned with dark red patterns.
Then, a roar unique to a Hollow echoed throughout the cavern.
Sensing the sudden, drastic mutation in the Spiritual Pressure of the person before her, along with the eerie bone mask on his face, Unohana's eyes widened slightly in spite of herself.
"This... is?"