The northeast direction has traditionally been called as Kimon 鬼門, the devil’s gate, through which the evil or malign spirits enter, and

“accordingly needed particular divine protection. It was the same belief that had spurred the construction of the great Tendai temple Enryakuji atop Mount Hiei, to the northeast of the city of Kyoto.” (Naito and Hozumi, p89)

One of historical documents on Enryaku-ji, titled Eigaku Youki jyou 叡岳要記 , well explains why Enryaku-ji became a temple to guard the Heian-kyo against the evil to enter through Kimon, as follows

     “According to Todo Engi 東塔縁起, …. When the Emperor Kammu 桓武天皇 abandoned Nagaokakyo 長岡京 and moved to Hean-kyo 平安京, thunderhead (雲峯) rose high in the northeast of the Imperial City. On the verge of Kimon’s inflicting brutal damage along the narrow path of storm (嵐徑成鬼門之凶害), Daishi 大師 (Saicho, 767-822) founded the original temple (latter called Ichijyo Shikanin 一乗止観院 ) on Mt. Hiei. The Emperor Kammu deeply implored Mt. Hiei to guard the Heian-kyo. Since then, Enryakuji became the monastic hall to pray for Honmeisei 本命星 of the Emperor (為皇帝本命道場)” (translated from 叡岳要記 ),

where Honmeisei is one of seven stars of the Dipper assigned to each person depending on his birth year with a specific earthly branch animal sign (see pp.199-201, KR).

The Sakuteiki also specifies the northeast as a taboo direction for setting tall stones, as in Subsection 25

      “A stone that is 1.2 to 1.5 meters tall should not be placed in the northeasterly direction. This will become a Phantom Stone, and, since it would become a landmark to aid the entry of evil spirits, people will not be able to live there for long. However, if a Buddhist Trinity is placed in the southwest, there will be no curse, neither will devils be able to enter,” (Takei and Keane, p189)

where a Buddhist Trinity is a set of stones called Sanzon Butsu No Ishi 三尊仏の石 which “refers to a trinity of deities usually containing a central Buddha figure attended by two” priests (ibid. p107).
   Similar taboo existed among stonemasons who worked for building castle foundation walls and keeps such as Tenshudai 天守台. Among the set of documents  titled Gotohke Monjyo 後藤家文書 and compiled by the Gotoh house worked for the Lord of Kaga Domain, the document titled Yuiko Hitori Den 唯子一人伝 instructs as follows:

      “The procedure to see directions is to place “jishaku” 磁石 (magnetic needle) on the center of the structure (郭の正中) and see it. This is to perceive Kimon 鬼門. If the corner of stonewall faces Kimon, be well aware of moving the corner  rightward or leftward so as not to face Kimon direction. Negligence causes a great curse on life (押事一向ならず命ニたたり有也)” (translated from referred sentences in KS p419, also in KJS p354).

Documents on the Northeast Direction