During the Sado period, Nichiren articulated his own teaching, distinct from the Tendai of his day. In this regard, his increasing self-identification with the work of Bodhisattva Superior Conduct is significant for several reasons. According to the Lotus Sūtra, Superior Conduct and the other bodhisattvas who sprang up from the earth are the Buddha’s “original disciples” (honge); that is, they are followers not of the historical Śākyamuni who attained enlightenment under the bodhi tree, but of the original Buddha, enlightened since the inconceivably remote past. In identifying his efforts with those of Bodhisattva Superior Conduct, Nichiren was claiming a direct connection to the original Buddha. In later years, he would state this explicitly: “Hidden in the fleshly heart within his breast, Nichiren maintains the secret Dharma of the sole great matter transferred from Śākyamuni, master of teachings, at Eagle Peak.” This claim was probably related to the idea that “the assembly on Sacred [Eagle] Peak is solemnly [present] and has not yet dispersed,” which occurs repeatedly in medieval Tendai texts. (Page 259-260)
Original Enlightenment and the Transformation of Medieval Japanese Buddhism