Shingon Tachikawa School

Shingo Tachikawa is a branch of Shingon Vajrayana (Shingon secret tantra teachings) that is based on “Rishu-kyo”2 and its teachings revere dakini-deity.
In the Kamakura era, a high monk of Shigon Buddhism, Ninkan, failed in an attempted assassination of Emperor Toba (Eikyuu Era [Eternal Era]) and was exiled to Izu as punishment. It is said that there, in the province of Musashi, Ninkan gave birth to the fundamental systems of Shingon Tachikawa in cooperation with the Onmyouji (spiritual medium) Kenren (from Tachikawa).
After that, the Tachikawa Sect spread and prospered to the point where it came to be the largest faction within Shingon Buddhism.
Furthermore, with the decline of the Kamakura Shogunate in sight, the Tachikawa Sect schemed to have the Imperial Family change its loyalties to prioritize Tachikawa over other sects. Emperor Godaigo, who mastered the secrets of Tachikawa, starting from Yoshino, spread it across the lands of the Southern Dynasty. After that, the Tachikawa Sect teachings were almost always present with the Southern Dynasty.
So with the decline of the Southern Dynasty, the Tachikawa Sect also fell into ruin.
…The suppression of the Tachikawa Sect didn’t occur because it was heretic or there was some problem with it’s teachings, it was due to its connection with the Southern Dynasty. Mount. Koya (the birth place of Koya-san Shingon Buddhism) lies within the territory of the Northern Dynasty, and almost all the authority figures in Koya held contempt for the Tachikawa Sect, and has all the Tachikawa scriptures destroyed.

Translator’s Notes
  1. ^ This stub presents a point of view that is somewhat different from what historians actually say about the Tachikawa Sect. The stub also seems to be written assuming that the reader has a decent idea of the history of Tachikawa Buddhism. Nasu basically took Tachikawa history and altered it a bit. Nasu does this in more than a few sections of this book.
  2. ^ Full name: Hanyaharamittarishishurishu-kyo; Sanskrit: Prajñāpāramitā-naya-śatapañcaśatikā.
Fate/EXTRA Material: Encyclopedia of Fate/EXTRA