"I will briefly explain the concepts regarding the Divine Keys and the Key of Blankness."
Lin knew Mei style was never to simplify the complex. She didn't care if others understood her theories and designs. When she opened the containment bay to reveal all eight Herrscher Cores to Lin, even he felt a sense of shock.
Though it had been said many times, these Herrscher Cores were the apex of Honkai creatures—the cores of Herrschers who controlled countless Honkai beasts and wielded powers like the laws of the universe. When they appeared together, did it make one think of the strength of the humans who defeated them, or the losses and sacrifices made in the process?
"Anti-Honkai God-Slaying weapons made of Soul Steel driven by Herrscher Cores—that is the definition of a Divine Key. The core lies in 'Herrscher Core driven,' meaning these are weapons used to fight Honkai with Honkai." Mei tapped a few times on the panel. The most dazzling core—the Core of Fire—was moved to the front for observation. "No matter the form of the weapon, it will not deviate from this definition."
Aside from the Core of the Second Herrscher he had briefly seen in Mobius lab, this was the first time Lin had observed a Herrscher Core—this seed of destruction containing a Herrscher's consciousness—at such close range. It was crystal clear like a gem, yet as unstable as a bomb about to explode.
Each core had a unique color, but Lin couldn't see them. He could only use the helmet's scan to identify them. There was only one core which, although gray, Lin felt he didn't need a scan to recognize. Like his own color perception, it had lost its original hue. Thus, it was also the most stable of all the cores—a crystal like a dead thing.
"Heh..." Mei noticed Lin had discovered that core. She didn't hide it, pulling the Core of Reason from the Previous Era closer.
"However, when I first designed the Divine Keys, I proposed the concept of an Extra Key—the Key of Blankness. This is the only 'Divine Key' that will not follow the standard definition, because it is not driven by a Herrscher Core, but rather, the Key of Blankness drives the Herrscher Core."
"This most stable Herrscher Core will serve as the permanent core for the Key of Blankness, allowing it to have combat power even without linking to other Herrscher Cores."
Mei explanation was unusually fast this time. Perhaps she thought that even if Lin listened politely, he might not take it all to heart. So she got straight to the point: "According to our plan, Kevin will use the Divine Key made from the Core of Fire. You will be the wielder of the Divine Key of Death and the Key of Blankness."
There was no need for shock. After his Project Soldier surgery failed, Lin had already suspected Mei would find other ways to compensate for his "flaws." The design intent for the Key of Blankness was exactly that—a Divine Key led by a pure human.
"...Are there planned wielders for the other Divine Keys?" Lin asked, staring at the core through the transparent isolation material.
"The Divine Key of the Core of Thunder will be given to Sakura. The primary forms of the remaining Divine Keys have not yet been determined." Mei added, before saying, "We will begin compatibility testing in half an hour."
"Phew... alright."
"Lin."
After finishing his business with Mei, Lin ran into Prometheus outside. Originally appearing as his support AI, Prometheus I now seemed completely independent, moving freely—much like a daughter who has grown up and become self-reliant.
"I am performing periodic system maintenance," Prometheus reported expressionlessly.
Come to think of it, Vil-V had specifically mentioned last night that Prometheus clothes were personally designed by her. Lin, on a whim, looked at Prometheus appearance, which he had seen countless times.
It looked like a modified military uniform in every respect, but with some of Vil-V's own hobbies added—like the combination of black tights and high boots, and black silk gloves.
"Lin, what are you looking at?" Even a moment's pause didn't escape Prometheus sensors. She tilted her head and asked naturally.
"Is your internal structure still mechanical now?" No matter how he looked at it, Prometheus body no longer had the doll-like joints from before, and her pupils didn't feel like the mechanical eyes that trigger the uncanny valley effect. To an outsider, she would just be a cold, expressionless girl. Lin wondered if Vil-V had used cloning technology to create a true human body and just modified the brain to insert an AI.
"Composed of 63% mechanical structures and 37% biomimetic structures."
Fewer biomimetic structures than before?
"So Lin does not need to consider whether I have sweat glands causing foot odor."
"..."
After delivering a joke that perhaps only she found funny—or perhaps she didn't find funny at all—Prometheus walked to Lin side, stood on her tiptoes, and whispered: "At 3:21 AM today, a corpse was found at Headquarters."
Lin turned his head sharply, staring intently at the expressionless Prometheus.
"An investigation is currently underway. No signs of struggle or traces left by the perpetrator were found at the scene."
It's happened again?
"Who is the deceased?"
"MSA-650, Private, Erwin."
"...I understand."
Lin once again thought of Chiaki passing by hurriedly this morning. Her soul-shattered expression looked as if she had done something irreversible. However, people should be investigating this. Prometheus likely warned him to be careful; Headquarters might soon experience something similar to a "Great Purge." But this time, the one in power was Mei.
"Grand Dr. Vil-V hopes you will participate in the investigation."
Vil-V...? Just as Lin took in the information and prepared to leave, he heard Prometheus mechanical voice say: "I will also participate in the investigation."
Lin had expected Prometheus to be involved. An AI is naturally helpful in cases requiring clues. If she had been involved in the last "Great Purge," she likely would have found information quickly even without insider knowledge. But why would Vil-V ask him...
"...Where is the crime scene?" Lin ultimately didn't overthink it. Vil-V had her own plans, and her logic was always eccentric.
At that moment, that strong premonition struck again.