[I]t is stated in the Concise Chronicle of Japan:
“When Grand Master Dengyō lectured on the Lotus Sūtra for Great Bodhisattva Hachiman in the Jingūji Temple of Usa, the Great Bodhisattva Hachiman declared in a divine message when he had finished listening to the Grand Master: ‘I have been unable to hear the voices of Buddhist sūtras. Fortunately, today I was able to see the venerable Buddhist priest and listen to him speak about the true teaching of the Buddha. Moreover, he has accumulated much merit for me, for which I am deeply grateful. How can I express my gratitude to him? I will donate my treasured robe to him.’ Thereupon, the Shinto priest who received the divine message opened the door of Hachiman’s palace, respectfully held up a purple robe and a purple sash, and made a request of the Grand Master saying, ‘With your great compassion, please accept these donations.’ Surprised at the miraculous event, subordinate Shinto priests all uttered that they had never seen or heard anything as wonderful as this. This robe donated by the Great Bodhisattva Hachiman exists today in the Sannōin Temple on Mt. Hiei.”
… During the second 10-day period of the 11th month in the 20th year of Enryaku (801), Grand Master Dengyō invited more than ten high priests of the seven great temples in Nara representing the six schools of Buddhism to his lecture on the Lotus Sūtra held on Mt. Hiei. Wake no Hiroyo and his brother Matsuna lamented after listening to him speak: “It is regrettable that this wonderful teaching of the One Vehicle doctrine has not spread widely; it is sad that the perfect harmony of the triple truth has not been revealed.” They also sighed: “Both young and old cannot do away with the roundabout way of the provisional teaching to free themselves from the chain of delusion.”
Thereafter, on the 19th day of the first month in the 21st year of Enryaku (802), Emperor Kammu visited the Takaodera Temple, where he ordered the high priests of the six Buddhist schools in Nara and Grand Master Dengyō to meet in debate on their respective theologies. None of the 14 scholar-priests of Nara were able to answer questions, and they later submitted a letter of submission: “Many sūtras and commentaries have been expounded in more than 200 years since the rise of Buddhism through the efforts of Prince Shōitoku. They have been fighting one another for theoretical supremacy without definitely answering which is the supreme teaching. Besides, the teaching of this most wonderful Tendai Lotus School has not been spread.”
Reflecting on this, I believe that the true teaching of the Lotus Sūtra had not been revealed before Grand Master Dengyō. What was meant by the Great Bodhisattva Hachiman must have been this when he said in his divine message that “he had never seen or heard of it.” There is no question about this.
The Lotus Sūtra, fascicle 4 (chapter 10) preaches: “You should know that anyone who expounds even a phrase of the Lotus Sūtra even to one person even in secret after My extinction is My messenger (…) He will be covered by My robe. ” Contemplating this, I believe that as Maitreya Buddha in the future will inevitably expound the Lotus Sūtra, Śākyamuni Buddha sent him a robe through Venerable Kāśyapa. Likewise, the Buddha sent one through the Great Bodhisattva Hachiman to Grand Master Dengyō for expounding the truth of the Lotus Sūtra.
Kangyō Hachiman-shō, Remonstration with Bodhisattva Hachiman, Writings of Nichiren Shōnin, Doctrine 1, Page 262-264