Deep underground was Uryū. He was walking along a sewage passageway after Silas gave him specific instructions for a task.
This passageway was truly a network of subterranean canals spread over the entire area of the Seireitei. Only those from squad four would ever bother entering it since they were the ones in charge of cleaning the tunnels. Anyone could travel through it without being impeded, so long as they knew where to go.
"That darn, Ichigo," Uryū spoke to himself. "I can't believe he's making me do all this work. I thought we were supposed to be rescuing Rukia together!" His voice echoed across the empty halls. There was not a single person underground, making it the perfect place for him to travel safely.
But why had Silas sent Uryū alone?
In the story, Uryū had faced Mayuri in a battle. He won, but it cost him his Quincy powers. Silas didn't want that happening again, so he thought of a new strategy: cause as much commotion in the areas he needed him to. If he fails, hide underground and only resurface to take up a disguise as a fake Soul Reaper.
There was a reason Silas had chosen the south gate to enter from. This was the gate closest to where squad eleven was stationed. Squad eleven was well recognized for their brute strength. Yet not all of them were strong enough to be considered worthy of being there. Uryū, whom Silas knew was capable of defeating hundreds of them, was sent there for the distraction.
The entire map of the Seireitei was known to Silas. It wasn't anything difficult to remember, considering each squad's location formed a maze going in a circle.
Because of that, he ordered Yoruichi to scour the area for information regarding Rukia's whereabouts, pretending to be clueless on the matter. Yoruichi tried to suggest that they stick together, but he boldly reminded her that they hadn't come here to play games. "We're here to save someone. Follow my lead, and I promise things will go according to plan," he said at the time.
Yoruichi couldn't find any flaw in Silas's words. His recent acts haven't failed yet, so she agreed on account that they all meet up on the morrow.
Silas himself had to act fast before Aizen would return to Central 46. This was because he knew that a captain's meeting was ongoing. The only time it was certain that Aizen wasn't watching him was when those meetings were taking place.
• • •
Having taken a different route in the underground passage than Uryū, Silas climbed to the surface and found himself in a rich area.
Jade-kissed cherry blossoms danced along pristine canals, their petals showering streets paved with moonlight-spun silver. Laughter and drinking rummaged through alabaster homes, where Souls wove silk kimonos under skies shimmering with stardust.
If memory served Silas well, he was around where squad five's district. More importantly, he was directly inside an area that belonged to a noble family.
Noble families have an unclear role within the Seireitei. There were only four of them, each carrying an influence over governmental institutions, such as Central 46 and the Soul Reaper Academy. The Kuchiki family was one of those four noble families, but the one Silas had ventured to was the Tsunayashiro family.
This family was never expanded upon in the animation. It was only ever mentioned in a light novel called "Can't Fear Your Own World". And the only character worth mentioning in this family was a Soul Reaper named Tokinada Tsunayashiro, the antagonist of the light novel. Tokinada would one day get himself promoted to the head of the family, eventually orchestrating a secret rebellion campaign against the Soul Society to replace the king. Ultimately, he would be met with defeat at the hands of Soul Reapers, Quincies, Hollows, and Fullbringers before being murdered by an unidentified assassin.
He had a very sadistic personality, adopting a nihilistic worldview of things. But what made him truly dangerous was his family's ancestral Zanpakutō, Enrakyōten!
Why had Silas been so warped into acquiring this sword when he already had Zangetsu? Was it truly the first thing he planned to do upon entering the Soul Society? By all means. And here is why: Enrakyōten had the innate power to mimic any Zanpakutō's abilities that its wielder had witnessed beforehand!
Silas melted through the perimeter wards, his spiritual powers masked by unwanted passersby. His heart calmed itself, desiring to possess one of this world's most dangerous Zanpakutō. He moved with the practiced grace of a predator, navigating moonlit gardens and koi ponds. Silhouettes of unaware guards were mere smudges against the walls as he snuck by them.
It hadn't taken long for him to discover exactly where this family hid this special weapon. Entering their ancestral shrine, he saw a stark monolith without any seals or bindings. Behind it rested Enrakyōten, its white and black hilt acting as a beacon that would serve him well.
Silas kneeled, the obsidian floor biting into his skin. The moment he touched the sword, Enrakyōten thrummed, sensing an encroaching Hollow. He countered with a wave of his own spiritual pressure to cease its apprehensiveness. The forces colliding with one another came to a halt, causing Enrakyōten to return to a calm state. He then held the weapon close to him, finding the heat-tempered blade to have been crafted well.
Footsteps were heard fast approaching the shrine. The spiritual pressures had to have been sensed, despite how much Silas tried to conceal them. "Who's there?" someone asked, entering the room. They were suddenly stumped after seeing a blinding light. When they opened their eyes, they saw none other than the head of the Tsunayashiro family.
"Be at ease," he said. "I was merely checking to see if our ancient heirloom was being well-guarded."
One such guard looked in the monolith and found the weapon still inside. They each asked the head what that light was, to which he responded that it must have been the moon's reflection.
Matter settled, the head relieved the guards of their duties, ensuring that things were safe. But the moment they left, it was only Silas standing inside the room. What the guards had experienced was nothing more than an illusion copied from Aizen's Kyōka Suigetsu!