The line of Japanese sovereigns, beginning with the seven generations of heavenly deities and five generations of terrestrial deities, is supposed to be followed by one hundred generations of human emperors (hyakuō). During the reign of the thirtieth human emperor, Emperor Kimmei, Buddhism was introduced for the first time from the country of Paekche on the Korean Peninsula to Japan. It has been over 260 years since then to the reign of Emperor Kammu, a reign of more than fifty sovereigns. During this period all the scriptures of Buddhism, as well as the six schools of Buddhism in Nara (Kusha, Jōjitsu, Ritsu, Sanron, Hossō and Kegon Schools) were introduced to Japan. Tendai and Shingon schools, however, were not.

“During the reign of Emperor Kammu, a poor monk, Saichō, a disciple of Venerable Gyōhyō of the Yamashinadera (Kōfukuji) Temple in Nara, lived. He was later called Grand Master Dengyō. Saichō studied thoroughly the doctrines of the six schools of Nara, which had been transmitted to Japan earlier, and Zen Buddhism without finding them satisfactory. Later he read the T’ien-t’ai school’s writings transmitted to Japan by Venerable Chien-chên (Ganjin) of T’ang China forty years or so earlier during the reign of Emperor Shōmu, and was awakened to the profound meaning of Buddhism.

Thereupon Saichō founded the Enryakuji Temple on Mt. Hiei in the fourth year of the Enryaku Period (785) in order to pray for peace and tranquility of the country. Taking refuge in the temple, Emperor Kammu named it the “Temple of the Imperial Guardian Star.” He gave up faith in the six schools of Nara, putting sole faith in the “perfect” Tendai School.

In the thirteenth year of the same Enryaku Period (794), the imperial capital was moved from Nagaoka to the newly founded city of Heian (Kyoto). On the nineteenth of the first month in the twenty-first year of the same period (802), the Emperor ordered fourteen scholars of the six schools of Nara, such as Gonsō and Chōyō, from seven great temples in the southern capital (Nara), to meet with Saichō in the Takao-dera Temple for debate. The brilliant scholars of the six schools could not answer even one question, keeping their mouths shut tightly.

The doctrine of five teachings of the Flower Garland (Kegon) Sect, the three-period teaching of the Dharma Characteristics (Hossō) Sect and the doctrines of two storehouses and three periods of the Three Discourses (Sanron) Sect were all refuted by Saichō. Not only were their doctrines destroyed but it also became clear that they were all slanderers of the True Dharma. Ten days later, on the twenty-ninth of the same month, an imperial edict was issued censuring the fourteen scholars of the six schools of Nara, who respectfully submitted a letter of apology to the emperor.

Successive emperors since then have devoted themselves to the Enryakuji Temple on Mt. Hiei in a way more filial than filial children serve their parents or more respectfully than the people respect their king. On behalf of the temple some emperors issued imperial rescripts, while others went so far as to bend the law.

Ankoku-ron Gokanyurai, The Reason for Submitting the “Risshō Ankoku-ron,” Writings of Nichiren Shōnin, Doctrine 1, Pages 147-148