The days flew by in an alternating blur of experimentation and study. Hasumi Ren's life fell into a strict, unchanging routine: handling medical duties at Squad 4 by day, and painstakingly calculating the spatial formulas passed down by Tsukabishi Tessai in his quarters by night. Occasionally, he would carve out time to visit the Kido Corps' secret chamber for face-to-face guidance from the Grand Kido Chief himself.
Anyone else would have been utterly exhausted by such an intense pace, but with the support of his system, Ren's learning efficiency far surpassed that of an ordinary man. Every concept Tessai taught him was instantly internalized the moment the fragments surged in. Intricacies that normally required endless practice to grasp could be flawlessly replicated after seeing them demonstrated just once.
From his initial shock to subsequent silence, Tessai had now grown completely accustomed to it. He had thoroughly accepted this reality. He had simply grown numb.
"Your form is excellent today." Inside the secret chamber, Tsukabishi Tessai nodded as he observed the spatial formula Ren had drawn. "The precision of this anchoring node is practically on par with my own."
Ren didn't look up, his spiritual pressure continuing to trace lines in the air. "You praise me too highly, Grand Kido Chief. It's just a matter of practice."
Tessai shook his head, offering no reply. "You have already mastered eighty percent of the spatial formula's framework. The rest isn't a technical hurdle; it's a matter of your total capacity of spiritual pressure. Your current spiritual pressure isn't sufficient to sustain large-scale spatial techniques. This is a hard threshold. It cannot be rushed."
Ren set down the formula matrix. "Understood. So for now, all I can do is optimize the formulas to their absolute limit. Once my spiritual pressure catches up, everything else will naturally fall into place."
Tessai nodded. "Speaking of which, was Aizen satisfied with the Garganta proposal you submitted?"
"It went well enough."
Tessai fell silent for a moment, then murmured softly, "That is good to hear."
...
Deep within the underground cavern beneath Sokyoku Hill, Kisuke Urahara squatted in front of a workbench, tinkering with a new device amidst a scattering of various components. He didn't look up when he heard the approaching footsteps.
"You're here?"
As Ren walked up to the workbench, Urahara placed the latest Garganta-opening blueprint onto the table. "An updated iteration. Take a look."
Ren picked up the document and flipped it open. As his eyes swept across the densely packed formula nodes, his brow gradually unfurled. "Impressive. The spiritual pressure transition at this node is much smoother than in the previous version." He nodded. "The previous iteration caused the spiritual pressure to erupt too rapidly, making it difficult to align and anchor the coordinates inside Hueco Mundo. This optimized version is a massive improvement."
Urahara looked up at Ren, a flash of surprise crossing his eyes. "You... can actually make sense of this?"
"Yes, I asked the Grand Kido Chief for some guidance."
Urahara blinked in surprise. "Tessai?"
"Correct," Ren replied without concealment. "He has researched spatial formulas for many years. When I approached him with questions, he was willing to teach me."
Urahara fell silent for a moment before a small smile tugged at the corner of his mouth. "That old friend of mine certainly keeps his cards close to his chest. I thought I was the only one in the Soul Society secretly researching these matters, but it turns out he isn't exactly a law-abiding citizen either." He set the document down, leaned against the edge of the workbench, and crossed his arms. "Though if it's him, I suppose it makes sense. Still, you're learning remarkably fast."
Ren offered no response.
Urahara looked at him, his gaze turning complex. "Ren, I've always been curious—just how do you study? The speed at which you absorb knowledge defies common sense."
Ren merely pondered the question without answering.
Urahara stared at him, remaining silent for a long while before letting out a sigh. "Very well. I'll continue optimizing the Garganta blueprint for you. Wait for my word."
Ren nodded. "All right."
A few days later, Aizen stood before a laboratory table, the latest Garganta proposal submitted by Ren spread open in front of him. His gaze rested on the intricate network of spiritual pressure nodes. Tosen Kaname stood at his side, hands resting flat against his thighs, his expression placid.
"Have you reviewed this proposal?" Aizen asked.
Kaname nodded. "I have."
"What do you think of it?"
Kaname paused for a brief moment. "My comprehension of spatial formulas is limited, so I dare not judge rashly. However, judging strictly by the completeness of the blueprints, Hasumi Ren's progress is far quicker than anticipated."
Aizen closed the folder and turned to look at him. "It isn't just quicker, Kaname. It is fast enough to defy all expectations. You have followed me for many years; you should know exactly what this Garganta technology means for our upcoming plans."
Kaname bowed his head. "I understand."
"Therefore, I want you to assist Ren with everything you have. You cannot match his technical aptitude, but he requires your exact level of execution."
Kaname's fingers tightened slightly into a fist before slowly relaxing. "Understood."
"Go on, then. Ren should be arriving shortly. Go and help him prepare for the experiment."
Kaname turned and walked toward the exit. As he pushed the door open, his footsteps faltered for a fraction of a second. Exhaling a heavy, suppressed breath, he strode out into the corridor.
Inside the testing area, Ren was busy fine-tuning a formula, his spiritual pressure weaving through the nodes. He didn't even look up when Kaname walked in.
"Lord Aizen has sent me to assist you." Kaname's tone was flat, but Ren could detect a subtle strain beneath the surface.
"Just in time. Help me monitor the spiritual pressure at node three. I can't tear myself away from this side right now," Ren requested.
Kaname stepped up to the workbench, picked up the formula matrix, and began his assessment. Channeling his own spiritual pressure into the node, he probed the intricate pathways.
Then, his brow knit tightly together.
He couldn't comprehend many of the formula structures. It wasn't an absolute lack of understanding, but rather that he could only grasp the barest surface of it all. The sudden transitions of the spiritual pressure nodes, the precise timing, and the method of blending Hollowified spiritual pressure with Soul Reaper Kido formulas were all entirely beyond the scope of his knowledge.
Gritting his teeth, he forced himself to try and follow Ren's train of thought. Fine beads of sweat broke out across his forehead, yet the formula nodes remained an absolute jumble in his mind.
"Is the spiritual pressure at node three stable?" Ren's voice drifted over from the center of the testing area.
Kaname went quiet for a moment. "...I am still observing."
In truth, he was entirely uncertain. But he couldn't admit he didn't understand. Lord Aizen had assigned him here out of trust. If he failed to perform even basic assistant work for Ren, how would Lord Aizen view him?
Taking a deep breath, he resumed inspecting the node. Every single node required exhaustive deliberation just for him to faintly grasp its purpose. His head throbbed with a dull ring and his spiritual pressure drained rapidly, but he didn't dare stop.
"Kaname, calibrate node seven for me." Ren's voice called out again.
Kaname's fingers froze for a brief second. He walked over to the location of node seven and injected his spiritual pressure. The pathways within his perception felt like a hopelessly tangled ball of yarn; he attempted to unravel them, but the threads only knotted tighter.
He set down the matrix board, exhaling a ragged, heavy breath. His mind was in absolute chaos.
"What's wrong?" Ren walked over.
Kaname tilted his head slightly. Ren's voice held nothing but calm composure. "It's nothing. Just slightly uncertain about a few parameters..."
Ren picked up the formula matrix and tapped it lightly with his fingertip. Spiritual pressure flooded the board, instantly straightening and organizing the chaotic nodes into perfect alignment. After offering a brief, casual explanation, he handed the matrix back to Kaname. "Try it again."
Kaname accepted the board and channeled his spiritual pressure back inside. This time, focusing his senses exactly as Ren had instructed, the messy nodes finally became somewhat clear.
Yet, he was still an immense distance away from true comprehension.
Kaname fell completely silent.
When he had first heard of the Garganta project from Aizen, he had assumed Ren would remain bottlenecked by this technology for a very long time. Spatial formulas were strictly taboo in the Soul Society, with practically non-existent documentation. Even for the exceptionally gifted, achieving a breakthrough required years or even decades of cumulative dedication.
But how long had it actually been since Ren took over the project?
They had started from the same baseline—in fact, Kaname had been introduced to spatial formulas many years before Ren, explicitly to build a foundation for their future experiments.
Yet right now, he couldn't even decipher the Kidō formulas Ren drew?
Kaname's fingers trembled ever so slightly as his breathing grew heavier. He felt completely lost in a sea of bewilderment.