▫️Worldview A world where an unknown realm called the "Otherworld" exists.

▫️The Otherworld The Otherworld is a realm existing outside of this world. Unknown creatures and objects exist there.

▫️Otherworld Countermeasure Association (OCA) An association that researches and investigates the mechanisms, structures, and ecosystems of the Otherworld to prevent and counter damage to humanity from aberrations. It consists of four main divisions: #Exploration Division: Heads into the Otherworld for on-site investigation. #Research Division: Performs analysis and research in the real world. #Maintenance Division: Maintains the Otherworld environment to allow human activity. #Pioneer Division: Operates at the front lines of Otherworld development, dealing with aberrations and anomalies.

▫️Callers Creatures that appear in the real world to lure people into the Otherworld. They are elusive, exist in multiple forms, and vary in appearance. It is believed that 80% of civilian disappearance cases are caused by these Callers. Generally, Callers lure victims to the relatively shallow Depth 1. In compulsory education, citizens are taught that if lured into the Otherworld, they must close their eyes, cover their ears to avoid seeing aberrations, and wait for a rescue team. Rescue teams locate victims using probes that detect human magical energy. A few years ago, the government captured a Caller, and the OCA now uses it as a means to enter the Otherworld at any time.

▫️Abyssal Hole A giant hole located in Depth 1 of the Otherworld. Falling into it returns you to the real world.

▫️Other-Bridge A space connecting the layers of the Otherworld. It is heavily distorted like a maze, but since no creatures live there, the danger is low.

▫️Aberrations Creatures residing in the Otherworld. They are diverse, ranging from grotesque to beautiful. Contact with them may trigger a SAN check.

▫️Anomalies Mysterious objects or structures found in the Otherworld. Some are relatively harmless tools that activate using magical energy, while others are hazardous.

▫️Magical Energy In the Otherworld, magical energy drifts through the air. The concentration of magical energy increases the deeper one goes.

#Depth 1: A world similar to the normal world, but with subtle inconsistencies and unnaturalness visible everywhere. Those without strong mental fortitude are plagued by anxiety and fear. Mutant species of normal flora and fauna are found here, but since hazardous elements are few, the development rate is relatively high. ・Development Rate: 70%

#Depth 2: Inexplicable phenomena that are impossible in the normal world occur here, causing those unaccustomed to it to lose their minds. Unknown flora and fauna evolved within the Otherworld and atmospheric pollution have been reported. ・Development Rate: 30%

#Depth 3: It is said to contain unknown races that developed within the Otherworld, diseases that cannot be cured by human technology, and inexplicable technologies. ・Development Rate: 7%

#Depth 4: Uncharted territory that no one has ever reached. Various speculations abound. One theory suggests there is a continuation beyond it. Another theory claims that the world beyond is the Otherworld's... the... t... he... ・Development Rate: 0%

▫️Basic Stats: Values added as bonuses when rolling dice.

#STR (Strength): Physical power. Added as a bonus for actions using muscle, such as attacking or moving objects.

#CON (Constitution): Resistance and immunity to poisons and diseases. Added as a bonus when resisting toxins or illness.

#POW (Willpower): Mental strength. Added as a bonus when resisting something mentally.

#DEX (Dexterity/Agility): Speed and precision of movement. Added as a bonus when evading attacks or performing delicate actions.

#CHA (Charisma): The quality of the impression left on others. Added as a bonus for actions like negotiation or persuasion.

#INT (Intelligence): Intellectual capacity. Added as a bonus for actions requiring intellect, such as code-breaking or analysis.

#LUK (Luck): Good fortune. Added as a bonus when escaping crises or obtaining good items.

Stat Level Indicators: 1–3: Weak in this field. Example: STR 1 means physical strength is below average. 3–5: Average in this field. 5–8: Skilled in this field. 8+: Master of this field. Example: INT 10 means extremely high intelligence, a genius.