Seidou {星道} Exorcism (say-dough)
"Look up at the stars and not down at your feet. Try to make sense of what you see, and wonder about what makes the universe exist."Many ghosts and baleful forces work their way through the Kaguyan Federation for uncertain reasons. These often take the forms of various monsters or harmful spirits, but can also come in varieties that influence the mundane such as a curse of misfortune or a germ spurring on a plague. To counter these effects, the three people groups of the Federation have their own methods. The Dalsup {달숲} People invoke the strength of the natural world and the skies, the Yueyue people perform physical acts of prayer and strength, and the Kaguyan People use magical formulas to seal the deal. Seidou Exorcism, while billed as a Kaguyan art, is a combination of all three methods. It incorporates the physical power and movements from the Yueyue, the powers of environmental leylines and the divinity of the stars from the Dalsup people, all wrapped up in an arcane ritual package as the original Kaguyans would do it. It is a practice that, when combined with the philosphies of others, achieves something great from the act of true unity. If only that lesson was learned by the majority of Kaguyans, to combat the true malady in the Kaguyan Federation.
History
Exorcism, or at least the purification aspect of it, wasn't a singular invention. It was a discovery, one the people awakening and settling in the land of the Kaguyan Federation needed to keep survivng there.
No one know why these corruptive entities appear so violently in the area, but it has been occuring long before the Three Kingdom Alliance began their Era system. The Kaguyan people, originally the Tsukibata of the lowlands, would call them Heigai, the Maladies, and construct arcane rituals and contracts to bind them and banish them. The Yueyue of the highlands would know them as Āisī, Grief, and liken them to ghosts and guilt made manifest, honing their physical and mental states to fend them off. The Dalsup of the coasts and waters called them the Busig, the Rot, and use their understanding of nature and strength of faith to cleanse them as they arose.
When the Wild Wall fell, and the assimilation by Empress Kaguya began, the three methods of exorcism began to meld together in a much more collaborative way than other aspects of Kaguyan society allowed. The arcane method gave the art its barriers and the recognition of the stars, the physical method allowed for proper diagnoses and protection for the Exorcists, and the nature method allowed for greater usage of the stars power as well as the end result with the Heigai returning to the Leylines to empower them once more. Thus did the art of Seidou Exorcism begin, and just in time too as the rising tensions and casualties of brutal assimilation gave rise to many lingering spirits and pieces of hatred.
It wasn't until the age of assimilation that the practice took on explicitly religious signifigance. The Stars had always held signifigance to the cultural groups of the area, but the Dalsup found divinity in just about everything, and the Yueyue saw the gods as more earth-focus beings. It was the hierophants of Empress Kaguya who conscripted most of the knowledge about The Astral Court and designated them as the primary pantheon of divinity for the Kaguyan people. As such, Exorcism became not just a cleansing ritual, but an act of religious worship as well.
This association also lead to the invoking of certain deities in the process of the Exorcism, and the rise of Mediums to empower them. Despite being in a time of intense cultural washing and shame, this actually gave the Dalsup people a small bump of individual notoriety, as their clerics and religious workers were more often than not divine mediums. Unfortunatly that bit of pretige faded as the role of the Medium became more widespread and melted into the process.
The popularity of the style and it's practitioners has risen and fallen in the ages, largely depending on how much it's needed at any given time. During times of chaos and crisis, they are indisputably necessary healers of the land and of magic. During times of peace, they are strange occultists or charlatans with many rumors swirling around them. When cultural tensions with rise, they'd be a point of ire for nearly all sides, as they take cues from each of the three primary groups of Kaguya, yet practitioners are often still subject to their biases, especially when Seidou is called purely a Kaguyan art.
In the modern day of the Federation, the entire society is having an arcane reneissance of sorts, including the art of Exorcism rendering it quite popular even in a time of piece. As more social work is being done to distinguish the Yueyue and Dalsup from the melting pot they were more-or-less forced down into, it's also become a useful symbol: an art made of three parts working together, not just conglomerating into one.
The longevity of either of these factors is up in the air, but so long as people live in the land, Exorcists will be in demand, and no matter the social optics of it all, any Exorcist worth their station will rise to the task.
Execution
The first action in Seidou is to find the target Heigai (弊害), also known as the Āisī (哀思) among the Yueyue or the Busig (부식) for the Dalsup. Essentially, it is the spectral or demonic entity causing the problem, the invading negative magical force. Once found, the next step is to isolate it with a barrier, most commonly in the shape of the five-pointed star many Exorcists use to represent the mortal soul.
Once the barrier is erected, the time for Exorcism has come. The method varies based on the particular Exorcist, but the most common way involves the chanting of an arcane prayer while performing a step-dance. The dance portion is how this style got it's name, as the Sei (星) in Seidou represents the stars. This is also why most exorcisms are performed at night, as the most effective step-dance will be one that mirrors the most polar constellation in ones specific area and time.
For weaker targets, the dance and arcane prayer will be enough, as the erected barrier will keep both the Heigai and the divine energy in its space, acting as an exorcising microwave of sorts. For stronger Heigai, this process will render them into a semi-physical form, in which the Exorcist will have to use other, usually more combat-oriented, skills to finish the job.
Once the Heigai has been defeated, another prayer of finality will be chanted, with the intent being to allow the power of the Heigai to return to the Leylines as untained mana, and for the souls of departed (if victims were taken) to be cleansed of the Heigai's actions, and therefore not have any debt on their ledger for the Astral Court.
Components and tools
Each Exorcist will have their own tools and methods to complete the fine strokes of the task, ranging from wands to charms to enchanted blades or their own body. Some materials are consistent, however, as professional Exorcists typically wear clothing enchanted to resist the corruptive nature of the Heigai, and the most common way of setting up a barrier is via magical talismans prepared ahead of time.
Participants
Most Exorcisms only involve a single exorcist and the target, especially in the case of a possessed person. If a Heigai is particularly powerful, sometimes groups of Exorcists will work together, with stronger and more notable Exorcists taking on deadly tasks.
In many cases, a Divine Medium is brought along in order to directly empower the Exorcist and/or the magic of the ritual with the power of the Divine. This is especially prevelant in Dalsup versions of exorcism, as Medium's of all kinds factor heavily into their faith.
Observance
Your garden variety exorcism can take place at any time, although the procedure will be different depending on which stars are in the sky. However, there also exist several specific exorcisms, or high-level exorcisms, for particularly ingrained or powerful Heigai that require specific timing and procedures, but that's on a case-by-case basis.
There is one key location, mainly used in Kaguyan-originating rituals, and that is Mount Senkyōshi {宣教師}, the largest mountain in the Federation and folkloric birthplace and home of the eponymous Empress Kaguya. Not only is that mountain brimming with the power of faith and potent natural leylines, it also provides a clear, undiluted view of the night sky and many constellations. So, powerful rituals are held there in utmost secrecy and security to deal with the most dangerous of Heigai.
Important Locations
Related Organizations
Related Ethnicities
This article shows a lot of thought and is a great first "Summer Camp" cut at worldbuilding! I want to encourage you to edit it to make it clearer up front (it took me a while to understand the context of it and the purpose of the ritual). Overall an interesting premise good start on a good article.