The crimson gem embedded in Astarte's chest emitted a faint, mesmerizing glow, carrying an almost intoxicating allure.
In truth, should this stone ever surface publicly, it would undoubtedly drive many to madness.
Rozen examined it with his Wise Eye, then nodded in satisfaction.
"The Philosopher's Stone seems to be functioning well."
—Philosopher's Stone.
A substance existing only in myth—the Holy Grail long sought after by Western alchemists.
Capable of substituting for any material in this world, in the hands of a skilled alchemist, it becomes a divine artifact with the power to create anything.
Some could use it to transmute base metals into precious ones, such as gold.
Others could brew elixirs of immortality, granting eternal life.
It bore many titles: Lapis Philosophorum, Stone from Heaven, Touchstone, Materia Prima of Gold and Silver, Red Tincture, Great Miracle, Magnum Opus, and even the Fifth Element.
Alchemists had pursued this substance for centuries, believing it represented the pinnacle of their craft. Across legends and myths, it appeared in various forms—sometimes solid, sometimes liquid, sometimes powder—but always with the luster of fresh blood.
Within the Atlas, there existed an arcane technique—
The art of creating the Philosopher's Stone, an ultimate memory medium capable of recording near-infinite information.
Stones forged through this method were also called Aqua Vitae (Water of Life). Not only could they heal all suffering, disease, death, and even vampirification, but they also served as precious materials for Atlas alchemists developing new technologies and mystic codes.
For instance, Hermes Trismegistus utilized the Philosopher's Stone for its information-recording properties. Among Atlas' rumored Seven Weapons Capable of Destroying the World Seven Times Over, most incorporated the stone as a core component. This alone demonstrated its versatility and priceless value.
Coincidentally, Rozen had also acquired a holy relic capable of bestowing life and will—the Keystone—in his previous world.
Thus, by combining Atlas' alchemical traditions with his research on the Keystone, Rozen crafted a Philosopher's Stone capable of generating vast amounts of life force.
Or, more accurately, a Stone of Life synthesized using the Philosopher's Stone as its base.
This Stone of Life was now embedded within Astarte, providing her with nearly limitless vitality. Whenever she summoned her Beast Vassal, the gem would pay the cost, allowing her to wield its power freely.
As for how it was embedded? For Rozen, it was trivial.
With his current mastery of alchemy, creating an artificial lifeform superior to Astarte from scratch would be no challenge, let alone performing such minor modifications.
"I'll just call it the Stone of Life."
After observing its operation, Rozen finalized its name.
"Soon, the gem will fully integrate with your body, making it impossible to remove. However, I've installed a protective spell—if it's ever separated from you, the Stone of Life will immediately shatter into dust. Be mindful of that, Astarte."
This precaution prevented potential misuse.
After all, if the Stone of Life fell into the wrong hands—while replicating it would be difficult (Rozen's techniques weren't of this world, and without Thought Acceleration or Thought Partitioning, analyzing its composition and creation would take centuries with high failure rates)—exploiting its life force would be simple.
For example, humans or Demons obtaining it could bypass the lifespan cost of summoning Beast Vassals, wielding tremendous power like vampires to summon and command otherworldly familiars at will—an undeniably tempting prospect.
Similarly, certain forbidden rituals requiring live sacrifices could use the stone's vast life force as a substitute, enabling catastrophic ceremonies without bloodshed. The consequences would be unspeakable.
Thus, Rozen took no chances—the self-destruct mechanism ensured absolute security.
"Command accepted."
Whether Astarte fully grasped Rozen's intent remained unclear, but she nodded impassively as always.
"Then I'll be off. Hold down the fort."
Rozen finally stood.
"Safe travels, Senpai."
Kanon bowed formally.
"Right."
Rozen smiled, gently patting Kanon's head—earning a shy but unprotesting blush—before leaving the Minamiya residence.
"Happy New Year, Senpai."
Yukina was already waiting in the elevator. Spotting Rozen, she immediately mirrored Kanon's formal greeting.
"Happy New Year. Sorry for making you wait."
Rozen had grown accustomed to Yukina's overly serious—or rather, rigid—demeanor and entered the elevator without further comment.
After some small talk during the descent, they shifted to the main topic.
"So, where should we begin our investigation?"
Yukina posed the question.
"Any ideas?"
Rozen countered instead of answering.
"Me?" Yukina responded carefully, "I considered gathering intel from the Lion King Agency. Should we visit their Itogami branch?"
"Did you contact them already?"
Rozen pressed.
"I tried, but no response. Probably due to the New Year?"
Yukina sounded uncertain.
Hearing this, Rozen smirked.
"That's... debatable."
At the very least, Rozen doubted the Lion King Agency's local office would take holidays after his return.
If anything, they'd be scrambling to monitor him and uncover his whereabouts during those missing two months.
Their silence likely mirrored Natsuki's—an attempt to avoid Rozen and Yukina's interference.
Unfortunately for them...
"Rather than chasing after branch personnel, why not go straight to your superior?"
Rozen suggested.
"Eh?"
Yukina blinked in surprise.
Rozen's expression turned profoundly meaningful.