Nelliel hadn't forgotten her oath to Kazuya. In order to honor her vow, she didn’t have to just value her life but also thrive in the treacherous landscape of Hueco Mundo. By virtue of her strength, she had overcome all hostile forces except for one harrowing encounter with a group of battle-hungry Adjuchas that forced her to flee.

Today, fortune seemed to favor her with a bizarre discovery — a sprawling cave that burrowed deep into the Hueco Mundo. Amidst the plethora of crumbling ruins that littered this realm, none ventured so deep below the ground as the one before her.

‘Perhaps I’ll stumble upon another treasure here.’

She had come across her lance in one of the ruins. The promise of another treasure led her deep within the ‘abyss.’ Towering, skeletal trees pierced the inky darkness around her. But any wonder at the surreal underground forest was quickly swallowed by the clamor of battle that reverberated through the still air. Her steps hesitated momentarily, until she sensed an anomaly — a Reiatsu both piercing and sinister, an energy signature that neither belonged to Hollow or Shinigami.

Drawn as if by a magnetic pull, she pressed on, each step accompanied by the torturous cries of Hollows, their voices thick with an unsettling terror and despair. These lamentations roused something primal within her, propelling her forward with redoubled urgency.

She arrived at a tunnel more ominous than any she’d seen, a maw bathed in an impenetrable darkness. Suddenly, the cries faded, replaced with a silence so absolute, it seemed as if the very air had been sucked away..

‘They all… died.’

Nelliel galloped into the dark expanse. A nauseating waft of blood enveloped the cave, coming from the Gillians’ corpses haphazardly strewn about the place. Death was everywhere, and it weighed her down with sorrow.

Ignoring the screaming instincts that warned her of imminent danger, Nelliel brandished her lance, charging through the bloodied tunnel like a gallant knight. The entity who killed these Hollows for no reason, she was going to put a stop to his slaughter using Kazuya’s creed — ending violence through greater violence.

‘I’m sorry, Kazuya, Harribel.’

She whispered an apology to the supposed rulers of Hueco Mundo, knowing that she might perish in the encounter. Someone who could single-handedly take down these Gillians alone had to be an Adjuchas of the highest level or, worse, a Vasto Lorde.

As Nelliel ventured deeper, the cave’s claustrophobic tunneling gave way to a colossal cavern. Two figures, frozen in the middle of what seemed to be an intense standoff, immediately caught her eye. One was garbed in a tattered black kimono reminiscent of Shinigami attire, his face obscured by a gazelle-like Hollow mask. An assortment of other Hollow masks adorned the brown fur coat that draped his shoulders, each one a grim trophy of his slain enemies. His katana and the Reiatsu signaled his affiliation with those purifying Hollows for the balance.

However, the Shinigami wasn’t the imminent threat against the Hollows, but the man facing the Shinigami. The man whose Reiatsu she had felt earlier. Sickly tall and pale skin, with disheveled brown hair, his attire was as strangely stylish — a fur-collared robe-like coat that exuded a sense of elegance. A katana rested in his grip, its handle almost ensnared by his unusually elongated fingernails, as sharp as daggers.

Oblivious to the Adjuchas’ presence, the two maintained their confrontation, their Reiatsus locked in an invisible but fierce contest of wills.

Muramasa was the first to break the silence. “A Shinigami coming to the aid of Hollows. Master may have been right somewhere in his twisted dream of eradicating the Shinigami.”

From a passionate soldier for the Gotei 13 to a man raising his blade at his father figure and slaughtering innocents — Muramasa’s Master became a different person after betrayals by men envious of his achievements.

The Shinigami, Ashido Kano, remained unfazed by Muramasa’s cryptic musings. “What are you?”

“It depends on who is asking. Is it the man who served the Gotei 13’s soldier or the beast sharpening his fangs by living among monsters?”

“...Both are me.”

“For the Shinigami, I’m Muramasa, a Zanpakutō Spirit serving Koga Kuchiki. For the beast, I’m a lost traveler crawling in the desert in search of an oasis.” He spread his arms, and his fingernails uncurled with audible clacks. “A crimson oasis of Hollow flesh and blood. These vile creatures… they’ll quench my thirst and satiate my hunger. The Hueco Mundo will become my banquet.”

Ashido loosened the grip on his katana. “Slaughter them as you wish. I’ll not stop you.”

He leaped towards a platform near the ceiling and disappeared into a cave.

Muramasa didn’t stop Ashido. Fighting a Shinigami, especially one close to Vice-Captain level, would have been an effortless task in his peak form. However, centuries of separation from his Master had deteriorated his strength. He could still use his abilities to make a Shinigami’s Zanpakutō rebel but it just wasn’t worth it at the moment.

Ashido’s departure was the best case scenario for Nelliel as she didn’t have to fight two opponents at the same time. However, she wasn't relieved. Her mind was hung up on Muramasa casually revealing his plan to slaughter all the Hollows in Hueco Mundo. She felt a visceral stir within her core. Her very spiritual energy flared up and recoiled at the thought of his pure evil. Unaware of the raw, intense emotions pushing her Reiatsu past her natural limits, she continued glaring at Muramasa.

“You will not kill anyone… I’ll kill you.”