Following the trail of Reishi.
Tsukasa's gaze eventually came to rest on a corner of the rocky cave. There, a trapdoor was embedded, fitting so seamlessly with the ground it was almost invisible.
Moss crept along the crevices of the stone surface; were it not for the rusted copper ring on the door panel, it would have been indistinguishable from the surrounding rock.
Clack.
Suo Tsukasa bent over, gripped the copper ring, and pulled upward with force.
Accompanied by the grating sound of stone friction, a staircase descending vertically was slowly revealed amidst the swirling dust.
Curiously, the light spilling out from the underground space was nearly as bright as the outdoors.
Without time to marvel at the wonders of the subterranean area, Suo Tsukasa descended the stairs, and the heavy door panel thudded shut above his head.
When Suo Tsukasa reached the landing of the stairs, the view before him suddenly opened up, causing him to catch his breath.
"So bright—"
"As expected of Urahara Kisuke."
Though he had anticipated this cavern would be large, the actual space was even more breathtaking than he had imagined.
The dome hung high like an upturned giant bowl, and light sources densely packed along the rock walls emitted a radiance that illuminated this underground grotto as clearly as daylight.
Since there were no legal practice grounds available, he simply had to find an illegal one.
In the Seireitei, when it came to the talent for breaking rules, no one surpassed the former 12th Division Captain Urahara Kisuke and the former 2nd Division Captain Shihouin Yoruichi.
The two were practically synonymous with lawlessness—one a mastermind of intellectual transgression, the other a powerhouse of action-oriented defiance.
Many of the secrets left behind by these two legendary figures still lingered in various corners of the Soul Society, and this miraculously engineered underground training ground was one of them.
Suo Tsukasa leaped down from the stairs, his Shihakusho snapping in the rushing air.
The height of over a hundred meters was crossed in an instant.
With his toes lightly tapping the ground, Suo Tsukasa landed beside a hot spring surrounded by mountain rocks.
Steam curled and rose into the air, the water's surface reflecting the glow from the dome.
Suo Tsukasa opened his bundle and placed it on a protruding rock, taking out the alarm clock, bamboo water flask, and medicinal pills, arranging them neatly before leaning his sword against the side of the rock.
Setting the alarm clock, he turned to a nearby clearing and immediately began his Kido training.
Raising a finger toward the ceiling, he began to chant the incantation slowly and clearly.
"Seeping crest of turbidity. Arrogant vessel of lunacy!"
As the incantation began, the Spiritual Pressure within his body surged like a breaking tide. Turbulent, dark spiritual light gathered at his fingertip, forming a roiling, pitch-black sphere of energy.
"Boil forth and deny. Grow numb and flicker. Disrupt sleep. Crawling queen of iron. Eternally self-destructing doll of mud."
"Repulse. Fill with soil and know your own powerlessness!!"
"Hado #90. Kurohitsugi (Black Coffin)."
As his voice fell, countless black bars of Spiritual Pressure manifested from the void, coiling and climbing. In an instant, they condensed into a pitch-black sarcophagus several meters high, completely enveloping the towering rock before him.
At the final note of the incantation, the Black Coffin took form. Countless sharp spears erupted from within the coffin, piercing through as the surrounding space trembled from the force.
The essence of Kido lies in understanding and control.
The visual of Aizen Sosuke—the spokesperson for the Black Coffin—and the written annotations from Captain Ukitake Jushiro had been looping in his mind all day.
At this moment, they transformed into fierce, ruthless destruction before his eyes.
"Whew—whew."
The Hado ended, and the Reishi dispersed. The once protruding rock had been ground into fine powder.
Suo Tsukasa knelt on one knee, the stray hairs on his forehead soaked with sweat. His ragged breathing echoed in the silent cavern.
"————Truly fascinating."
Although it had consumed ninety-nine percent of his Spiritual Pressure just to release a "budget" version of the Black Coffin, his face was filled with the satisfaction and joy of a dream realized.
Bracing his knee, he slowly stood up, walked to the previous rock, and downed a bottle of pills in one go.
Then, he stripped off all his clothing, tossing them haphazardly onto the rocks by the spring.
Splash—
Suo Tsukasa's naked form dove into the hot spring, sending up a spray of water.
The warm current instantly enveloped his body, as the spring water and the internal medicine slowly nourished his parched Saketsu (Binding Chain) and Hakusui (Soul Sleep).
"Haa—that's the stuff."
After a long while, Suo Tsukasa surfaced from the pool, leaning back against the edge of the spring with a long sigh.
While he wasn't sure how this medical hot spring had been formed, he could clearly perceive the profound mysteries contained within it.
The spring water was like a master of Kaido (Healing Kidō), tightly adhering to his Saketsu and Hakusui, continuously stimulating and assisting the recovery of his own Spiritual Pressure.
Paired with his self-made pills to replenish physical strength, it was an invincible match—a perfect pairing!
Feeling the Spiritual Pressure rapidly restoring within him, his fatigue faded bit by bit.
His thoughts drifted, and he couldn't help but think with a hint of regret: It's a pity my memories regarding Tenjiro Kirinji of the Zero Division are too sparse. If only I could find the original version.
However, the effects of this hot spring were already far beyond expectations. Suo Tsukasa gently closed his eyes.
He allowed the warm water to wrap around him, enjoying this brief moment of relaxation.
Dozens of minutes later.
Suo Tsukasa leaped out of the water. Being alone, he didn't bother getting dressed and returned to his previous spot in the nude.
"Again!"
Taking a deep breath, he began the chant once more.
"Seeping crest... Hado #90. Kurohitsugi."
The Black Coffin rose again, and he again fell to one knee.
Swallowing pills, soaking in the spring, restoring Spiritual Pressure, continuing the training—this cycle repeated endlessly within the grotto.
Every ebb of Spiritual Pressure was for the sake of a more turbulent convergence the next time.
Gradually, the volume of that pitch-black sarcophagus began to grow at a rate nearly imperceptible to the naked eye. The change was tiny, but it was steady and continuous.
Time slipped away bit by bit during his cultivation.
Drrrring—
When the clock hands reached the set position, the alarm's copper hammer vibrated rapidly, striking the bells on both sides. The agitated noise echoed between the rock walls.
Suo Tsukasa dispersed the Spiritual Pressure at his fingertip, and the pitch-black sphere vanished like flowing sand.
He walked to the rock, pressed a finger against the vibrating alarm to silence it, and the cavern returned to stillness.
"It's about time to go back."
Suo Tsukasa turned and walked to the hot spring, letting the water wash over his shoulders one last time.
Moments later, he returned to the bank and used fire-based soul arts to evaporate the moisture from his body.
He put his Shihakusho back on and counted the number of unopened porcelain bottles on the rock, frowning inwardly.
"The consumption exceeded my expectations."
"This is troublesome."
The medicinal resources of West Rukongai were already scarce, and he had used the majority of them over the past two years.
Meanwhile, the high-quality medicinal resources of the Seireitei were firmly controlled by the Central Pharmaceutical Institute, which was under the direct jurisdiction of the Tsunayashiro family—the head of the Four Great Noble Houses. They never circulated raw materials externally, only selling expensive finished medicines.
Even on the bustling commercial streets, one wouldn't find a single medicinal herb shop.
"It seems I'll have to find a way through the 4th Division."
"It's a pity Sister Kiyone is out on a mission."
Suo Tsukasa's fingers brushed against the empty porcelain bottles, his eyes clouding with deep thought.
Kotetsu Kiyone's older sister, Kotetsu Isane, was the Lieutenant of the 4th Division and had a very kind personality. If she acted as a middleman, it would not only be much more convenient but also increase the chances of success.
As for Captain Ukitake Jushiro, the thought had crossed his mind, but Suo Tsukasa had just received a Kido manual from him. To trouble him again for personal cultivation did not align with his principles.
Mainly, it was because the pills weren't irreplaceable; food could also replenish physical strength, though the sheer volume needed made it cumbersome to carry.
"I'll have to make do with food for now and wait until Sister Kiyone returns."
Suo Tsukasa's thoughts shifted quickly, and he soon estimated the amount of food he would need for his next training session to ensure the pills lasted until Kotetsu Kiyone returned from the World of the Living.
He then packed his sword, leaving the rest of his gear on the spot.
On the way back, the night was already deep.
Only the sound of the wind brushing past remained, along with Suo Tsukasa's own steady heartbeat.
Avoiding the patrolling ordinary guards all the way, he eventually returned silently to his small courtyard.