Seishuku Temple is a long standing organization where its main monastery is located on top of a mountain in a remote region of Japan. As one of few places in the magic community where the Onmyou Agency holds no influence, it stands as one of the major symbols of independence.
While the organization in general is secular, it readily accepts anyone who wishes to become part of it regardless of their background. Thus it has a mixture of people from all over the country who are often outcasts of society because of their powers and those who have nowhere else to go. However, because the temple maintains a policy of "don't ask, don't tell" regarding the histories of its members, unlicensed practitioners and magic criminals are also rumored to congregate there, making it an excellent place for gathering information as well. Due to this, it is nicknamed the "dark temple" among outsiders.
Magic can be freely used here, and the various functions and rules are managed and enforced by "ajari", or priests, as they are called in the temple.
After the passing of the Onmyou law reform a year prior to Volume 10, the Seishuku Temple split into two factions: the older Conservatives, who want to continue their traditional values and their ways without interference of Onmyou Agency, led by the head monk Jougen, and the Reformists comprised of the younger generation envious of conveniences of the outside world, who wish to side with the Onmyou Agency so that the temple would open up for their benefit.
Tensions were high and arguments between priests and members occurred daily, leading to a consistently charged atmosphere. When emissaries from Onmyou Agency arrived with the dual purpose of absorbing the organization while smoking out the whereabouts of Harutora, things took a turn for the worse and negotiations between the Temple and Agency broke down. With the arrival of Harutora, the situation came to a head and spiraled out of control, leading to a violent magic battle and the complete destruction of the main temple.
Seishuku Temple has existed much longer than the Onmyou Agency with a history and reputation that spans centuries. Originally it was a sect of Shingon Bhuddhism before it switched to its current religion of Neopaganism after the war. Its main deity is Myouken Bodhisattva, the guardian god of magic who its worshipers have linked to the Yakou party because Myouken was also known as "North Star Deity". This was because of Yakou's strong ties to the temple which play a part in him establishing Imperial Onmyoudou. The ajari of that time, being so enthralled with his supreme gift for magic, view him as a fitting incarnation of their god. Yakou was particularly close to Jougen's predecessor, Head Priest Shinra.