Tutorial/Ridu Encyclopedia

Based on current human understanding, Hollows are invisible spatial domains that appear spontaneously in space and expand at certain rates. The space within a Hollow is chaotic - once you stumble in, it's nearly impossible to find your way out. The Etheric Matter that permeates these spaces not only corrupts humans and other materials but also gives birth to dangerous Ethereals.

Hollow Zero is New Eridu's oldest and largest Hollow, with its complex structure and treacherous environment striking fear into all who speak of it. Having once triggered a catastrophe that nearly destroyed the entire city, it has become synonymous with terror.

According to currently available official information, humans are still in the process of exploring Hollow Zero's internal structure. Hollow Zero consists of irregular sectors, with each sector's depths randomly spawning one or more powerful Ethereals, while the ecological environments vary drastically between different sectors.

Besides Hollow Zero, New Eridu currently has six other major "Great Hollows" under intensive monitoring: Cretan, Lemnian, Pursenas, Hawara, Solove, and Papago.
While these six Great Hollows may not match Hollow Zero in size and activity, they remain staggeringly massive and, for various reasons, impossible to eliminate. For many years, they've coexisted with the city, silently mocking humanity's fragility and insignificance.
When Hollows reach a certain scale, they begin to proliferate like a living organism, spawning new "Companion Hollows." Most of the Hollow disasters frequently occurring in New Eridu are caused by Companion Hollows that stemmed from the Great Hollows.
When a Companion Hollow first appears, entering quickly and destroying high-activity entities can effectively halt its growth and likely wipe it out entirely.

Eleven years ago, Eridu experienced an unprecedented Hollow disaster. The activity of Hollow Zero grew exponentially in a short time, and its size expanded rapidly, swallowing vast areas of Eridu's most prosperous districts - the Pluto Quarter and Minerva Quarter. After the disaster, Eridu authorities poured massive resources into disaster relief and tried desperately to contain Hollow Zero's expansion, but their efforts proved largely futile, with the Defense Force suffering particularly devastating casualties.
Left with no choice, Eridu's leadership at the time decided to detonate 14 Shiyu Towers along the city's southwest to northeast axis. The explosion created a massive chasm that cut through the city, but it successfully reduced the amount of matter available for Hollow Zero to corrupt and convert, effectively curbing its activity. However, by the time Hollow Zero's size and activity returned to normal levels, Eridu had been reduced to ruins, with countless people displaced...

Later, when the survivors wiped away their tears atop the ruins and the city was renamed New Eridu, this catastrophic disaster was officially dubbed the fall of the Old Capital.

Carole Arna was an Advanced Research Director at Helios Academy, and also the teacher who raised us with great care and affection. In the eyes of the citizens, however, she was to blame as the mastermind behind the Hollow Zero incident that led to the tragic fall of the Old Capital.
During the fall of the Old Capital, Teacher Carole saved our lives, but we were too young and powerless to do anything but watch as she was taken away by a terrifying giant hand. We became Proxies to investigate our teacher's whereabouts and to uncover the truth behind the fall of the Old Capital and clear her name.

The Helios Academy was once Eridu's top research institution and a special school where my sibling and I studied, and where we acquired a special smart crystalline lens. After the fall of the old capital, the academy's former site became a restricted zone inaccessible to ordinary folk, as the Minerva Quarter where it was located was consumed by the Hollow.

Known in full as the "Hollow Deep Dive System," it was initially proposed by Arche, and developed by the Helios Academy with technical support from the Marcel Group. Professor Carole was the lead researcher. The core components of the HDD currently in our video store were salvaged from the Helios Academy when the old capital fell — a legacy passed down from the Helios Academy.
The HDD system aimed to overcome the challenge of observing Hollows from the outside. After substantial investment of resources and manpower, researchers finally discovered a special signal capable of penetrating the Hollow barrier. Because the signal exhibits intense Ether interference upon exiting a Hollow, it must be restored to a readable form within a simulated Hollow—like environment at the receiving end. Further research revealed that the human body was the optimal medium for simulating this Hollow environment.
The smart crystalline lens implanted in us siblings acts as a modem for Hollow data, connecting to our brains and enabling them to simulate Hollows. Even as the best-suited hosts, receiving such powerful Hollow signals strains both our cerebral and physical systems. And since the HDD draws heavily on our physiological energy, our aptitude for Ether has been compromised, forcing us to rely on Eous to explore Hollows, as it houses the HDD system's adaptation and conduction devices.
Beyond communication capabilities, the HDD also integrates Hollow data storage and computation functions. Although a hacker attack damaged much of our locally stored Hollow data on the HDD, Fairy's arrival helped us implement cloud storage for Hollow data.
Later, we learned from Mayor Mayflower that Professor Carole had been researching ways to reduce the HDD's power consumption on the human body. Using the professor's remaining documents, the mayor helped us optimize and upgrade the HDD, allowing us to now enter Hollows directly without relying on Eous.
Yet regarding both the secrets behind the HDD and those surrounding ourselves, we still know very little.

Sacrifices are a special type of Ether Active entity capable of operating outside the Hollow. Their creation appears to be the result of human manipulation.
On the eve of the old capital's fall, the giant hand that kidnapped our teacher possessed the power of a Sacrifice. Years later, we sensed that same ominous presence again while searching for the prototype with Belobog Heavy Industries.
Years ago, Landon, the Exaltist leader active in the Janus Quarter, created a medicine that could transform living people into Sacrifices, though its effects were highly unstable. Judging from the Bringer incident, the Exaltists' technology to create Sacrifices has clearly improved.
There are still many unsolved mysteries surrounding the Sacrifices.

A mysterious organization documented since the Eridu era, they believe that humanity will ultimately evolve into a new form that coexists with the Hollows. They harbor an intense devotion to the so-called "Creator," and records indicate this Creator has intricate connections to the Hollows.
Throughout the Exaltist's history, they have repeatedly initiated dangerous operations affecting civilians, leading city authorities to designate them as a dangerous illegal organization. While the Exaltists appeared to fall silent in recent years, they never truly disappeared.
Based on current intelligence, although they belong to the Exaltists, Bringer and Sarah are neither Landon's successors nor subordinates, and they don't know Landon's orphan, Dina. They are merely collecting the Sacrifice remains left behind by Landon, but the true purpose behind their actions remains a mystery.

The TOPS Alliance, short for The Outstanding Paragons Alliance, consists of New Eridu's most financially powerful and influential corporate conglomerates. TOPS wields significant influence across all sectors of urban operations, to the extent they're considered equal rivals to the municipal authorities represented by the Mayflower family.
Despite their long-standing poor reputation among citizens, TOPS remains synonymous with "quality assurance," attracting numerous corporations vying for a coveted spot in their ranks.
TOPS regularly conducts performance evaluations of its members, and once a company's strength declines, even well-established corporations with long histories aren't spared from being shown the door.

"Drowned Ideal" is a term coined by Moss, characterized by entities that maintain the same appearance as the corrupted ones but possess different identities - they are "how people dream themselves to be."
When observed through the Perception Technique, it becomes evident that Drowned Ideals aren't human, but rather share the same ethereal manifestation as other Miasma-derived beings.
In essence, they are Miasmic products formed when the empty Miasmic environment of the Lemnian Hollow corrupts people, guiding and transforming their consciousness and memories.
The Miasma traps the person's true form and materializes their dreams from their memories, replacing their original self with this simulation living within the Hollow.

"The Creator" is an extremely dangerous and mysterious entity mentioned across multiple intelligence sources.
As for Their true nature and purpose, nearly all available information points to one conclusion — "unknown."

According to the Bangboo Lockspring, the Creator's status far surpasses that of the Exaltists, the secret organization that once caused massive chaos.
The Creator is supreme, and the Exaltists merely caught Their fleeting attention by chance.

The mysterious enemy that was defeated by the Proxy and their companions in the depths of the Lemnian Hollow wasn't the Creator's true form, but rather a Messenger created by the Creator.
This Messenger appeared to be some kind of chaos entity, with an incredibly complex composition including Miasma, Lumite ore, and a special metal, fused with Sarah's flesh — willingly sacrificed by the Exaltists. Moreover, it seemed to have stolen a trace of power belonging to Sunbringer, the first-generation Void Hunter.

What the Creator truly is remains unknown to all.
Only one thing seems certain—
That battle in the Lemnian Hollow was far from the end.
Perhaps it was merely a single breath released when the Creator began to stir.

"Void Hunter" - the highest official honor in New Eridu, bestowed personally by the mayor upon heroes who achieve extraordinary feats in combating the Hollow Disaster.
However, in the city's shadows, a more ancient and forbidden term closely tied to the "Void Hunter" title circulates among the few who know—"Void Hunter Weapons."

Carole Arna once mentioned there seems to be some kind of unavoidable "price" behind every weapon.
This theory has found preliminary confirmation in two known items believed to be "Void Hunter weapons."

Qingming Sword: The sacred treasure of Yunkui Summit. Its user, Ye Shunguang, while gaining immense power, suffers from irreversible backlash effects including memory loss and sensory deterioration.
Ethereal-Slaying Katana - Tailless: The current Void Hunter Hoshimi Miyabi's blade. Reportedly, earning this blade's recognition comes at a tremendous cost, and prolonged use will gradually corrupt its wielder.

A mysterious high-ranking official of the Krampus Compliance Authority once mentioned the term "Void Hunter Weapons" during an internal discussion, linking it to a certain organization's secret plans.
This suggests that Void Hunter Weapons are not merely individual armaments, but may be tied to complex power plays and struggles among New Eridu's upper echelons.

Is the title of "Void Hunter" genuinely just an "honor," and nothing else?
Are these so-called "Void Hunter Weapons" truly meant to combat the Hollows, or do they themselves share a deeper, more dangerous connection to the Hollows' secrets?
The truth continues to lie buried in the darkest depths.

Roscaelifer is a classified aerial special zone, established to ensure the continuous and stable production of "Rosetta Data." Built upon secrecy and advanced Porcelloy technology, it is jointly maintained by humans and Bangboo.

The Five Central Departments form the core power structure that keeps Roscaelifer operational. Comprising five main divisions, they collectively manage governance, data, defense, technology, and external relations. What makes this system unique is that it is co-governed by three independent individuals who branched off from the original "Sunbringer."

Eldreda Sunbringer runs the Administrative Affairs Department. As the highest decision-making body, it establishes regulations, coordinates operations across all precincts, and directs the overall functioning of Roscaelifer.

Dracaene Sunbringer runs the Central Computing Department, whose core mission is to calculate the critical Hollow source data known as Rosetta Data.

Lindverne Sunbringer runs the Airspace Patrol Department. It is responsible for maintaining the security of Roscaelifer and its surrounding airspace.

Flint Workshop is based on the islet of Vyrium and operates with a high degree of autonomy. Possessing the world's only Porcelloy forging technology, it has honored an ancient pact for generations, providing Roscaelifer with equipment research and development, as well as hardware support.

The External Strategy Department serves as Roscaelifer's bridge to the outside world, coordinating relations between the special zone and the other districts of New Eridu. The ESD maintains close ties with the Marcel Group, and its personnel often operate under Marcel Group cover identities when carrying out official duties in New Eridu.

An Etheric Other is an externalized manifestation composed of highly concentrated Ether energy, one that can be controlled by an individual's consciousness. Its formation relies on the immense Ether energy latent within its host and typically requires the absorption of large quantities of a special stabilizing medium such as Porcelloy. An Etheric Other is not an independent lifeform, but a projection and extension of its host's inner power. Pyrois is the Etheric Other born from the power within me.

To truly master Pyrois, I had to fully accept my own power and my past, transforming from one who merely endured fate into one who guides it. With the help of the CCD, I successfully summoned it into reality for the first time.

When that dangerous presence answered my call and took form at my side, I finally understood: we were never enemies fighting for control.

It is the shadow I can no longer hide, and the flame I have reignited. It is the future I must face and learn to live alongside.

A Singularity Leakage is a high-risk spatial anomaly that appears around the Scamall Hollow. It is caused by the Hollow's proximity, which results in extremely high concentrations of free Ether in the surrounding environment. When Ether becomes locally overconcentrated, it distorts the laws of space, creating an overlapping dimension that temporarily intersects with part of the Hollow's interior.

In the past, such singularities were rare and posed limited danger due to the Hollow's relatively stable activity. However, with the awakening of "The Creator," the Hollow's activity has intensified, causing Singularity Leakages to appear more frequently and with greater danger, now evolving into violent spatial anomalies capable of consuming life and threatening regional safety.

A Enchainer is a high-risk spatial anomaly that appears around the Scamall Hollow. It is caused by the Hollow's proximity, which results in extremely high concentrations of free Ether in the surrounding environment. When Ether becomes locally overconcentrated, it distorts the laws of space, creating an overlapping dimension that temporarily intersects with part of the Hollow's interior.

In the past, such singularities were rare and posed limited danger due to the Hollow's relatively stable activity. However, with the awakening of "The Creator," the Hollow's activity has intensified, causing Enchainers to appear more frequently and with greater danger, now evolving into violent spatial anomalies capable of consuming life and threatening regional safety.