Darkness, like a tangible tidal wave, instantly swallowed the entire stronghold.
It was no ordinary darkness, but the physical manifestation of Spiritual Pressure. It felt cold, heavy, and bore a suffocating sense of oppression.
Hasumi Ren stood at the end of the corridor, watching the darkness expand in all directions. Wherever it swept, all sound was swallowed and all light was annihilated. Only Tosen Kaname's Spiritual Pressure surged frantically within the blackness.
"Fifth Seat Tosen!" Ren's voice echoed into the void.
There was no response. The darkness continued to spread, devouring everything around it—sound, sight, and perception were all completely erased.
Ren gritted his teeth and flared his own Spiritual Pressure, attempting to resist the encroachment of the dark. But Tosen Kaname's Bankai was simply too overwhelming. This darkness was not a mere physical phenomenon, but an absolute suppression born of sheer spiritual weight. He could feel his senses fading away entirely, rendering even the act of breathing difficult.
Ren abandoned his attempts to stop him. Turning on his heel, he sprinted toward the administrative section, distancing himself from the epicenter of the outbreak. Relying on his memory of the layout, he did everything he could to salvage the research files. Moving blindly through the dark, he used his sense of touch to locate the filing cabinets, stuffing whatever documents his hands brushed against into his pockets.
A quarter of an hour later, the darkness finally began to recede. Tosen's Spiritual Pressure gradually withdrew, and the suffocating weight dissipated along with it.
Ren looked up toward the corridor. Tosen stood in the center of the ruins, cradling the glass container tightly in his arms. His face was devoid of expression, but his blind eyes were shut tight.
Behind him lay a scene of absolute carnage. The researchers, the guards, and the test subjects who hadn't even had the chance to resist were all collapsed across the floor, their Spiritual Pressure entirely gone as their lives came to an end. The ruins were covered in charred marks and severed limbs, the air thick with the pungent stench of blood as fires blazed fiercely. Scattered all over the ground were the residual traces of a Soul Reaper's Zanpakuto and fractures from Kido explosions.
Ren emerged from the office area, a bulging backpack slung over his shoulder. He stared at the glass container in Tosen's arms, inside of which floated a faint glow. Suspended within the container was a soul fragment—the residual spirit particle crystal of Kakyo, which had served as the fuse to ignite Tosen's madness.
At this moment, Tosen appeared dazed. His usual composure and coldness were entirely gone, leaving him looking utterly devastated.
Ren stood before him, a few singed pages of salvaged research notes held between his fingers, still glowing with stray sparks. He glanced back at the flames ignited by the Kido explosions, his voice perfectly flat yet laced with a biting chill.
"The stronghold is completely destroyed, more than half of the spirit energy resources are ruined, the same goes for the research data, and you made such a massive scene... Once we return, you had better think long and hard about how you are going to explain this to Vice-Captain Aizen."
Tosen's footsteps paused, but he offered no response. He merely cradled the glass container, following blankly behind Ren as they walked back toward the Seireitei.
A dead silence accompanied them the entire way.
...
Aizen sat before the laboratory bench, the report for this mission spread out in front of him. His gaze did not rest on the paperwork, but rather on the two individuals standing before him.
Tosen Kaname stood to the left, cradling the glass container in his hands with his head lowered, completely silent. Ren stood to the right, his bulging backpack resting by his side, his expression serene.
The laboratory was deathly quiet, filled only with the sound of their steady breathing.
"So, the mission was a failure." Aizen's voice was calm, betraying no emotion whatsoever.
Tosen's body trembled slightly. "Yes."
"The reason?"
Tosen remained silent for a long time. "I... lost control."
Aizen did not speak further to him. He turned his head, looking directly at Ren. "You tell me."
Ren lifted the backpack, pulling out the salvaged research data from inside and placing it on the bench.
"While executing the mission, Fifth Seat Tosen discovered the object he is currently holding inside the stronghold. Following that, he lost emotional control, fully unleashed his Bankai, and eliminated everyone within the facility. The majority of the experimental resources were destroyed. I was only able to salvage these files and a portion of the materials."
Aizen looked over the documents. He then let his gaze sweep back and forth between Tosen and Ren, as if gauging something. Ultimately, Aizen's eyes settled on the object in Tosen's arms.
"What is this?" his voice asked very softly.
Tosen's fingers tightened. Gritting his teeth, he uttered the name. "This is... Kakyo."
Aizen's brow twitched slightly. He had heard this name before. It belonged to Tosen Kaname's dearest friend, the woman who had been murdered by the Tsunayashiro family.
Furthermore, Aizen was highly familiar with the state of the fragment presented inside the container. It was precisely how a Soul King fragment looked after being extracted from a soul.
"To think a fragment of her soul would appear in such a place."
Tosen didn't answer, merely lowering his head a fraction more.
Aizen fell silent for a moment, then stood up and walked over to stand before Tosen. Tosen's body stiffened slightly, but Aizen merely took the glass container from his hands. He lifted it to eye level, gazing at the faint glow within.
"This is Kakyo's soul fragment?"
Tosen's voice was hoarse. "Yes."
Aizen said nothing. He scrutinized the sphere of light closely, letting his Spiritual Pressure circulate around his fingertips as he probed into the container. After a short while, he withdrew his energy and returned the container to Tosen.
"How can you be certain it belongs to her?"
Tosen's fingers gripped the glass tightly. "Your subordinate... recognizes her Spiritual Pressure."
Aizen stared at him, remaining silent for a long time. "Are you sure?"
"Positive."
Aizen nodded, choosing not to press further. He turned around, walked back to the laboratory bench, and sat down.
"The mission failed, the stronghold was destroyed, the resources were utterly lost, and the commotion caused was immense. Someone must be held accountable for this."
Tosen dropped to one knee. "It is my fault. I am willing to bear full responsibility."
Aizen didn't speak; he merely looked at Tosen with a profound, unreadable gaze. Only after a long while did he speak.
"We will address the matter of responsibility later." He paused. "What do you plan to do with this fragment?"
Tosen's fingers trembled slightly as his heart endured an intense conflict. Ultimately, he gently lifted the container in his hands, yet it looked as though he were letting go of an old weight at the same time.
"Lord Aizen, please fuse it into the Hogyoku."
Aizen's eyebrow twitched slightly. "Fuse it into the Hogyoku?"
"Yes. This is the only thing I can do for her. Dwelling on past events no longer serves any purpose... If this can lend strength to the peaceful new world of our future, I am certain she would be willing to do so."
Aizen fell silent for a brief moment. He extended his hand, took the container, and looked at the faint light flickering inside. His fingers lightly traced the edge of the glass, as if lost in thought.
Then, he returned the container to Tosen.
"The Hogyoku does not lack such a minor shard of the Soul King. Since this is something highly precious to you, then keep it close."
Tosen was stunned. "Lord Aizen..."
Aizen looked at him, his gaze perfectly serene. "Take her with you, and together, witness our new world."
Tosen's lips trembled as tears rolled down his cheeks. He knelt on the floor, cradling the container in both hands, weeping uncontrollably.
...
Following that, Aizen no longer looked toward Tosen. He turned his head to look back at Ren.
"Ren, you did well to salvage these documents during this mission."
Ren bowed slightly. "Just doing my duty."
Aizen nodded, saying nothing more. He stood up, walked to the laboratory bench, and began sorting through the documents.