▫️Worldview A world where a mysterious realm known as the "Otherworld" exists.

▫️The Otherworld A world existing outside of our own. 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 mitigate damage to humanity. It consists of four main divisions: #Exploration Division: Travels to the Otherworld for on-site investigation. #Research Division: Analyzes and studies data within the real world. #Maintenance Division: Develops the Otherworld environment to allow human activity. #Pioneer Division: Operates at the front lines of Otherworld development, dealing directly 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 missing person 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, they must close their eyes, cover their ears, avoid looking at 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 massive hole located in Depth 1 of the Otherworld. Falling into it returns you to the real world.

▫️Otherbridge A space connecting the different layers of the Otherworld. It is severely distorted like a maze, but since no creatures inhabit it, the danger is low.

▫️Aberrations Living creatures within 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 energy increases the deeper one goes.

#Depth 1: A world similar to the normal world, but with a sense of wrongness and unnaturalness lurking everywhere. Those who are not mentally strong are plagued by anxiety and dread. Mutated versions 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 the uninitiated to go insane. Reports include unknown flora and fauna that evolved within the Otherworld, as well as atmospheric contamination. ・Development Rate: 30%

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

#Depth 4: Uncharted territory. No one has ever reached it. Various speculations abound. One theory suggests there is more beyond it. Another theory suggests that the world beyond is the... world... and... the... rest... ・Development Rate: 0%

▫️Base Attributes: Values added as bonuses when rolling dice.

#STR (Strength): Physical power. Added to actions involving muscle, such as attacking or moving objects.

#CON (Constitution): Resistance to toxins and disease. Added when resisting illness or poison.

#POW (Willpower): Mental fortitude. Added when resisting something mentally.

#DEX (Dexterity): Speed and precision. Added when evading attacks or performing fine motor tasks.

#CHA (Charisma): The impression one leaves on others. Added during negotiations or persuasion.

#INT (Intelligence): Intellectual capacity. Added to actions requiring intellect, such as decryption or analysis.

#LUK (Luck): Good fortune. Added when escaping crises or obtaining rare items.

Attribute Scale: 1–3: Weak in this area (e.g., STR 1 means below-average strength). 3–5: Average. 5–8: Skilled. 8+: Master (e.g., INT 10 means a genius-level intellect).