Senkaimon
Only a handful of soul reapers were dispatched to the Senkaimon after Shinji filled them in on what happened. Most of the dispatched were from the 4th and 12th Division, where fatalities from the former were minimal during the Wandenreich invasion. Overseeing the duty to retrieve the corpses falls on the 12th Division captain and the president of the Shinigami Research and Development Institute, Mayuri Kurotsuchi.
Unlike the other soul reapers, Mayuri always wears heavy make-up on his face. The black face paint covers much of his face, leaving thin white lines going up his face and a white nose. He wears a long, golden headdress which curves back to his mid back. Underneath his chin are two opposite facing strands from the mask. On the backside of the headdress the Twelfth Division symbol is painted. Beside him is his lieutenant, Nemu Kurotsuchi, an artificially-made human being whom he treats as his 'daughter' in a sense that she is his "greatest creation made"
Accompanying him is 4th Division Captain Retsu Unohana. She is a soft-spoken woman who addresses everyone she meets with honorifics, yet despite her demeanor everyone fears her strength. Unohana has the appearance of a slender and very youthful woman with blue eyes and black hair. She wears the standard Shinigami captain shihakushō apart from using an obi instead of the normal sash, which hides her well-endowed bosom. Her hair is long and is always worn as a large braid down the front of her body.
"When you told me that you needed my help, I assumed it was just another one of those Quincy desperately looking for an escape route. I didn't expect to come to whatever this unsightly scene in front of me" Mayuri flatly commented at Unohana
"Ara, I thought you weren't fond of things like this, Mayuri-dono?" she politely retorted with a smile on her face
"There is nothing to smile from this scene… and it's Mayuri Kurotsuchi for you. I hate such honorifics"
Mayuri approached one of the black substances left behind during the fight. He wiped a part of the sludge with his fingers and rubbed it to his thumbs. Taking it close to his eye, he finally made a discovery
"Interesting"
"What is it?"
"This substance left behind by our dear intruder, it has traces of reishi from a quincy–"
"So the perpetrator is one of–" Unohana cuts his explanation off
"I prefer if you let me continue to explain" Mayuri gently scolds her, waving his hand at her as a gesture to calm down
"As I was saying, this substance alone has three distinct properties; two of which I can remember. One, there are huge traces of reishi, a common characteristic found from a quincy; the other has traces of souls commonly found from a zanpakuto– notably the sword of one Ichigo Kurosaki"
Unohana let out a small gasp as Mayuri stressed out the specifics of the second property he discovered from the sludge. From what she could remember from the other reports, Ichigo was being treated from his injuries during their fight with Yhwach…
… while his sword was broken in half, with the upper half gone.
Perhaps that intruder manifested from the latter part before engaging in combat with Kensei and Shinji, and escaping Soul Society.
I am well familiar with the spirits residing in our zanpakuto, but for one to fully manifest into a sentient being capable of damaging another zanpakuto and bringing death like this; It seems unfathomable to me.
"But you said there were three properties, perhaps the third is the one you can't figure it out" Unohana added, pointing out what Mayuri said earlier
"Astute thinking. This is something that struck my curiosity. This may be different but it seems to shift between both a quincy factor and a zanpakuto spirit. Perhaps I should take more of these substances and study them from my laboratory, if I have the time."
"Perhaps it's not a great time to do it"
The two captains agreed to study it for some other time, given the circumstances. Mayuri then called out his lieutenant, giving her some orders
"Nemu, have them bring the bodies to my lab."
"Understood, Mayuri-sa–"
She was cut off by a faint sound of a horn. Mayuri looked on at Nemu and immediately realized something was wrong. Unohana caught on to their expressions as well.
The sound of the horn was gradually getting louder, along the sounds of a chugging train as well. The soul reapers were confused as to why a train was heading towards Senkaimon. As for the three of them…
A train? Wait!
Impossible!
Both captains and Nemu realized what was about to approach towards them at high speed–
"EVERYONE, FALL BACK NEAR US"
The soul reapers immediately heed both captains' warning as they took a few steps back. Those who were not able to move in time were quickly dragged away by Nemu one by one.
Unohana and Mayuri both put up a Kido barrier in unison, hoping to at least slow it down for a few meters
"Here it comes"
"Everyone, brace yourselves"
The kototsu made an impact with the gate with great force, it made a sound equivalent to a C4 explosion. As the dust settled in, the soul reapers were utterly surprised. Despite the huge force of the impact, the gate was structurally sound, save from the trainwreck that became a huge barrier itself.
Mayuri immediately took down the barrier and checked the substance flowing out of the wall. Now it has two very distinct properties; the unknown one he found earlier…
… as well as the one from the kototsu
"Now I know what our very violent interloper is capable of; he can assimilate living beings and take their power as his own" Mayuri pointed out right in front of the others
Unohana expresses concern from his findings.
A being that can assimilate and recreate their powers by his will. If I were to encounter him…
Images from her previous years flashed into her mind as she thought about it. One that heavily contrasts her outgoing personality.
The final image shows her facing a young, feral boy wielding a sword with chipped edges, in a lifeless environment.
… I don't think I can even win against him.
Ishida Residence, Karakura Town
In the family archives of the residence…
A pile of books has been scattered to the floor, half open.
A middle-aged man began to put the scattered books back into place, displaying a pained look in his eyes. As he returned them one by one, he begins to mutter a name out of anxiousness
Uryu…
Suddenly, he sensed a slight distortion within the archives, followed by a loud thud.
The man immediately took action, summoning his Heilig Bogen in his hand as he took cover onto a shelf. His weapon was small, perfect for taking down a single individual in close-quarters.
He slowly walked through the cover, hoping to catch the intruder by surprise. With his weapon on one hand, he prepares to attack as he peeks out–
"I suggest you put the weapon down. You're creeping me out"
The man lit up his eyes in shock. Something sharp was pointed behind his back.
It was the intruder, wearing a black leather jacket with a gray hoodie, with his hands, or rather his 'left blade', pointing at the man's nape.
The latter immediately dispersed his weapon, utterly knowing that he is in a greater disadvantage. He turned around and faced the intruder.
A cold sweat dropped from the back of his head as he saw the difference in their spiritual pressure. Still, he maintained his composure
"First things first; where am I?" the intruder raised a question
"You're in Kitakawase Prefecture in Karakura Town, specifically the archives of the Ishida residence. My name is Ryūken Ishida, and you are trespassing in my property" He answered with annoyance in his face.
"My name was Alex Mercer, and its not nice to meet you" Mercer shot back at him as he turned his blades back into a normal hand.
"Good to know you Mercer-dono. Now leave"
Rather than taking his leave, he shot back with another question.
"This feeling, it's the same when I consume that guy with golden hair. Perhaps you must be one of those 'quincies' those soul reaper wannabes were talking about"
That question itself raised alarm bells from Ryuken. What does he mean by 'consumed'? How did this man know what he is?
He shot a glare at Mercer
"I detest being called a 'quincy'. And those 'soul reaper wannabes' you were talking about are exactly what you thought. Perhaps I'm surprised that you were able to sneak off undetected from the Gotei 13. They might have burned you into a crisp right away"
"Unlikely, considering it was already war-torn when I came from there"
…
"What do you mean 'war-torn'? What happened there?"
Mercer certainly got his attention.
"Perhaps I'll make a trade: You give me information on what you are, and I'll give you the news on what happened there. Nothing lost here"
Ryuken looked at Mercer as he mentioned the specifics of his so-called deal. For some reason, this intruder suddenly became interested in his origins.
"I'll add a condition: Tell me what are you and I'll tell you what am I. Otherwise, the deal is off"
That…won't hurt
"Deal"
The two went on through the deal, discussing everything about themselves;
Ryuken went first. His species originated a millennia ago, scattered throughout the world with the sole purpose of eliminating hollows. However, their excess elimination poses a threat to the balance of souls, forcing the shinigami to eradicate every single one of them.
He was born as a pure-blooded quincy, and was arranged to be married to another pure-bred woman, Masaki Kurosaki. However, an encounter with a soul reaper fighting an artificially-engineered Hollow left her infected by the latter, forcing her to undergo Hollowfication with the said soul reaper. He then married another quincy, Kanae Katagiri, and together they had a son named Uryu. However, Yhwach performed Auswahlen to reclaim his strength, at the cost of both Masaki and his wife. This event left him embittered to the point that he became cold towards his son.
Mercer's turn came next; he was a scientist responsible for studying the Redlight virus, during which he and his team created a more potent strain named Blacklight. When Blackwatch initiated a purge to prevent information from leaking out, he took a vial sample as a last resort before he was gunned to death. However, he collapsed onto the sample, causing it to restructure fatally damaged organs, which brought on to his resurrection, at the cost of his memories. He saved the city from being decimated by a nuclear bomb, only to nearly bring it to ruin a year later when he lost faith in humanity.
They both became sympathetic towards each other's situation. Ryuken can only understand why Mercer had to do what he did back when he was still living in New York, being no stranger to selfishness and their worldly desire. Mercer on the other hand, can imagine what it felt like to lose a loved one. He had to save Mercer's sister Dana multiple times during the first outbreak, only to be turnedaway by her when he started the second one. He had also faced his adversary, James Heller, whose wife he indirectly killed.
Holding up to the end of the deal, Mercer informs him that during the time he arrived at Soul Society, he intervened in a fight between the Soul King's son, Yhwach, and Ichigo Kurosaki, during which he had assimilated the former's left eye and killed his right-hand man, Jugram Haschwalth. The former escaped from the soul society by a shadow, while he had to leave through the Senkaimon and into the Precipice world, stating that he has been looking for a way out for two months inside there.
Ryuken expressed shock at what he did.
To be able to fight head-on with Yhwach, and injure him, is pretty much an achievement itself. Just what are you, Alex Mercer?
Mercer immediately sensed something that made him take his leave. Ryuken was about to stop him when he asked this…
"Ryuken, where's your son right now?"
It hasn't been long since he last saw him rummaging his office desk, trying to find an answer about their origins.
"He may be in a riverbed, why is that?"
"That old bastard, they're coming to conscript him into their ranks"
Alarmed, Ryuken immediately stood up and tried to follow Mercer.
He may be as cold-hearted as ever, but deep down, he still loved his son so much. Mercer saw through his emotions and allows him to follow suit, giving him a precaution:
"Just stay a few distance away from me. You don't want to get caught"