[This chapter serves as a compendium of knowledge within the novel. It explains the worldbuilding and the fundamental systems of the story. The information is gradually revealed throughout the narrative, but is gathered here for convenience. As such, minor spoilers may be present.]
— General Information
◆ Grimoires
Grimoires are magical books used to slay Night creatures. Any human, regardless of age, may obtain one, provided they are spiritually mature and fully self-aware. Grimoires are divided into five tiers. Their power increases in proportion to their numerical rank.
• I
• II
• III
• IV
• V
Each tier possesses its own distinct type of grimoire. Because of this, a person's grimoire alone is enough to determine their tier.
◆ Owners
Those who possess a Grimoire are referred to as Owners. After getting a Grimoire from a Grimoire Library, they begin fulfilling their duties as its bearer.
◆ Grimoire Libraries
Grimoire Libraries are locations where Grimoires descend into the world. They are usually replenished automatically during the night. Within these libraries, Grimoires choose humans they deem worthy and bind themselves to them.
In many cases, Grimoire Libraries also serve as focal sites for the Caleostra.
◆ Caleostra
Caleostra are seeds that manifest either within the Night Curse Realm or, in rare cases, from Night creatures themselves. Once activated, they open Gates that allow Night creatures to pass into the real world.
For this reason, Owners must locate Caleostra and, once they open, enter the Caleostra Trial.
◆ Caleostra Trial
The Caleostra Trial presents an individual or group with a trial originating from the past, present, or future of the Night Curse Realm. These trials involve preventing disasters or fulfilling specific objectives. Failure results in the complete annihilation of the participant's soul.
◆ Night Curse Realm
The Night Curse Realm is a world of another dimension. Certain portions of it are connected to the real world through Ruins. Anyone who enters a Ruin is transferred into the Night Curse Realm. Night creatures inhabit this realm, and when a Caleostra Phenomenon occurs, they may cross into the real world.
If the area connected to a Ruin has not been claimed, Owners should first seize control of its Altar.
◆ Altar
Altars are structures that govern specific territories within the Night Curse Realm. Through an Altar, individuals who entered through a Ruin may return to the real world.
Whoever claims an Altar becomes the rightful owner of that territory, and the land itself becomes their domain. Even if the Owner dies, ownership of the territory does not transfer.
— Common Terminology
◆ Pages
Pages are weapons, armor, or accessories obtained by slaying Night creatures. Though difficult to acquire, their rank always matches that of the defeated creature.
◆ Night Mirrors
Night Mirrors are replicas of Night creatures. They usually share the same rank and class as the original creature.
◆ Spiritual Energy
Spiritual Energy is an invisible force that can only be sensed, not measured directly. It is consumed to cast spells and can regenerate naturally while at rest, especially during sleep or meditation.
◆ Soul Fragments
Soul Fragments are elements that strengthen an Owner. They enhance the bond between human and grimoire, increase spell efficiency, and deepen the Owner's understanding of their grimoire. In many cases, they also improve physical abilities.
◆ Soul Ranks
Soul Ranks indicate the level of danger posed by creatures and humans. They are divided into seven stages and are generally strengthened through overcoming Caleostra Trials.
• Dormant
• Awakened
• Blessed
• Nightnorn
• Great
• Legend
• Solacis
The ranking system for Night creatures differs slightly.
• Dormant
• Awakened
• Cursed
• Nightmare
• Great
• Mythical
• Terror
◆ Rankers
Humans are referred to according to their Soul Rank.
Dormant — Owner. The stage immediately after obtaining one's first Grimoire.
Awakened — Reader. Through repeated entry into the Night Curse Realm, the language of Runes becomes engraved into their consciousness, allowing them to read their Grimoires independently.
Blessed — Genius. Capable of concealing their Grimoire within their mind or casting two spells in one time.
Nightnorn — Philosopher. Able to wield three spells at once and eligible to form Contracts. Additionally, they may enter the Night Curse Realm at any time during the night, when they want.
Great — Saint. Can enter the Night Curse Realm at will and use magic even while their Grimoire is hidden within their consciousness.
Legend / Solacis. These ranks have never been reached by humanity. What lies beyond them remains unknown.
◆ Contracts
Contracts are pacts formed between Grimoire's True Owners (Grims) and Owners, mediated by their emissaries. Through such agreements, humans may obtain overwhelming power, at the cost of a sacrifice.
◆ Classes
Unlike humans, Night creatures possess Classes, which define their nature.
• Beast. The weakest and least intelligent type.
• Predator. Intelligent enough to select its prey. Highly dangerous in physical combat.
• Monster. Capable of facing multiple humans alone. Exceptional speed and endurance make them extremely lethal.
• Serpent. A class capable of independently using magic, often specializing in spiritual attacks.
• Tyrant. Can create its replicas of creatures with lower rank and class. Possesses superior strength and intelligence.
• Demon / Devourer Classes yet to be encountered by humanity.
— Abilities
◆ Blessings
Beneficial traits bestowed upon humans.
◆ Curses
Harmful traits granted to neutralize Blessings.
◆ Spells
Magic created through Grimoires. Each Grimoire possesses its own unique type of Spells. Spells affect both humans and Night creatures alike.
◆ Core Spells
The heart of a Grimoire. Its most powerful and dangerous spell. Discovering it requires a profound understanding of the Grimoire itself.
◆ Spell Name
A magical name assigned to a person. It usually carries no direct benefit and is most often used as an alias.