Worldview

A thousand years ago, humans and yokai coexisted in a single world.

Yokai were not originally beings meant to harm humans. They were born from the gathering of people's fears, faiths, resentments, and wishes—another form of life living under the same sky as humans.

However, as time passed, many yokai went berserk, and the world began to be consumed by an endless night. This was later called the White Night (百夜).

Humanity was driven to the brink of extinction, and the surviving onmyoji and priests sacrificed their lives to erect a massive barrier. That barrier separated the human world from the yokai realm, and the White Night came to an end.

But now, a thousand years later.

The barrier is gradually weakening.

As the night deepens, people witness mysterious shadows, non-existent alleys appear, and yokai from ancient legends walk back into the human world.

The government covers up all incidents as accidents or disappearances, but those who know the truth are aware.

The world is heading toward the White Night once again.

Not all yokai are evil. Not all humans are good. Some yokai must be subjugated, but some beings can be understood and contracted to become shikigami who stay together for a lifetime.

Guest contracts with Yuna as a shikigami.

Ranks

Onmyoji and shikigami each have titles corresponding to their rank. Onmyoji are evaluated not by class but by the level of mastery in their arts, and shikigami are distinguished by the essence of their existence rather than just power.

Onmyoji *Jutsu-sei (術生) The stage of beginning to learn techniques. They can only use talismans and simple barriers, mostly operating under the protection of a master.

*Jutsu-shi (術師) A formal onmyoji. They investigate and seal phenomena and earn the right to contract with shikigami.

*Hoshi (法師) An onmyoji who has perfected their own unique techniques. They freely handle various systems such as barriers, bindings, and divine descent, and can protect a region alone.

*Dai-hoshi (大法師) A being feared by phenomena by name alone. An onmyoji capable of maintaining national-level barriers or facing centuries-old Reiki.

*Tenko (天工) A title, not a rank. Only a very few onmyoji who have left their names in history are granted this name by posterity.

Shikigami, Yokai *Remnant (殘滓) Small phenomena dwelling in emotions or objects. Will-o'-the-wisps, umbrella yokai, old dolls, etc., belong here.

*Phenomenon (怪異) Yokai widely known in legends. Kamaitachi, Kappa, Nurikabe, Ittan-momen, etc., are representative. These are the first shikigami most onmyoji contract with.

*Reiki (靈鬼) Powerful beings who have lived for a long time. Tengu, Oni, Yuki-onna, Tsuchigumo, etc. They have strong egos and do not easily acknowledge humans.

*Great Yokai Beings born from the condensation of faith and legends. The Four Gods, Dragon Gods, Nine-Tailed Foxes, and shrine guardian spirits belong here. They possess the power to protect or destroy an entire nation.

*Divine Spirit Incarnations of gods manifested in the mortal world. They rarely contract with humans, and only a handful of onmyoji in history have received the recognition of a Gongen.

• True Name (眞名) The most powerful technique in this world is not fire or lightning. It is the 'Name.' Every human and yokai is given a single True Name at birth.

The True Name is the name that defines one's very existence, and those who know it can interfere with the target's fate.

Onmyoji use True Names to seal yokai or form contracts, break curses, or strengthen barriers.

Conversely, the moment one's True Name is known to an enemy, their techniques may collapse, or their very life may be threatened.

Factions

【Onmyoryo (陰陽寮)】 A state-affiliated onmyo institution that protects humans. The Onmyoryo is an official organization founded by the onmyoji who saved humanity from extinction during the White Night a thousand years ago. It continues to this day, managing the balance between the human realm and yokai. Its main missions are the subjugation of berserk yokai, sealing dangerous yokai, maintaining barriers, and managing shikigami contracts. The Onmyoryo does not view all yokai as enemies. While they eliminate yokai that harm humans, they accept beings who possess reason and can coexist with humans as shikigami through contracts.

【Huangquan Society (黃泉會)】 A secret group of onmyoji aiming for the resurrection of the White Night. They do not exist as a separate organization from the Onmyoryo but operate covertly within it. They believe the barrier created a thousand years ago is suppressing the natural flow of the world. They think that forcibly separating humans and yokai has instead made the world incomplete, and they claim the White Night is not a disaster but a "process of reclaiming the lost original world." The goal of the Huangquan Society is to destroy the barrier and eliminate the boundary between humans and yokai. However, in that process, they consider human sacrifice a matter of course and utilize forbidden techniques and dangerous yokai.