The Earth is a planet created solely by God that respectively supports a large variety of life, including bacteria, humans, creatures, and animals. The planet is nearly 5 billion years old and is located in the Solar System, within the Milky Way Galaxy. Entities like angels and demons can manifest on Earth via possession in the use of vessels. Others can appear physically by assuming human form.

Within the first billion years of Earth's history, life appeared in the oceans and began to affect the atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.

Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism. A "giant impact" collision with a planet-sized body is thought to have been responsible for forming the Moon. Over time, the Earth cooled, causing the formation of a solid crust, and allowing liquid water to exist on the surface.

During the dawn of creation, it is said that when Cain murdered his brother Abel out of rage and jealousy, the Earth itself was said to be cursed with Abel's very blood, which was spilled from the massacre. The emergence of the first murder committed by Adam and Eve's first born, would later spread throughout the land and infect those who possess a darkness within their hearts.

Humans are the dominant species on the planet. They are often considered as one of the greatest creations of God, and unlike angels and demons, they are neutral in the war between Heaven and Hell, not including hunters whom are aware of the supernatural occurrence. Though many humans worship God and believe in the existence of Heaven and Hell as well as the occult, most remain unaware of the many supernatural entities roaming the planet.

In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all the species of life that ever lived on Earth are extinct. Estimates of the number of species on Earth today vary widely; most species have not been described. Over 7.3 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humanity has developed diverse societies and cultures; politically, the world is divided into about 200 sovereign states.

As humans roam the Earth, so do monsters. Monsters often spend their time preying or toying with the humans, seeing them as nothing but playthings or food. While they are only known through legend, the monsters keep their existence secret by hiding themselves or posing as humans.