Nichiren implied in 1272 in “Open Your Eyes” (“Kaimoku-shō”) that he was himself a manifest reincarnation of the Bodhisattva Superior Conduct, the leader of all the bodhisattvas who had emerged from the open space under the earth in chapter 15 of the Lotus Sutra. In identifying his efforts with those of Bodhisattva Superior Conduct, Nichiren was claiming a direct connection to the original Buddha. Later on, in the Muromachi period, some exegetes in one of the Nichiren branches would go further, claiming that Nichiren was himself the original Buddha of chapter 16.

But Nichiren also makes explicit in his writings that the long-lived Śākyamuni, and also the underground bodhisattvas, are existent within our own minds. He quotes this passage in chapter 16 of the Lotus Sutra: “The duration of my life, which I obtained through the practice of the way of bodhisattvas, has not yet expired. It is twice as long as the length of time stated above: 500 dust-particle kalpas.” He comments, “This reveals the bodhisattva-realm within our minds.” For Nichiren the realm of bodhisattva practice expressed by the primordial, enduring Buddha, as well as the bodhisattva practice that leads to such a buddha life, is an interior, psychic realm imaged within the minds and hearts of current practitioners.

Nichiren continues that the underground bodhisattvas of chapter 15, “who have sprung out of the great earth, as numerous as the number of dust particles of 1,000 worlds, are followers of the Original Buddha Śākyamuni who resides within our minds.” Nichiren here declares that this “original Buddha” lives as a potential within the minds of Buddhist devotees.

But the effect of the enduring Śākyamuni is not merely limited to the mental or subjective realm for Nichiren: “When the Eternal Buddha was revealed in the essential section of the Lotus Sutra, this world of endurance (Sāha-world) became the Eternal Pure Land.” Nichiren describes the external world of saṃsāra as now, immediately transformed by Śākyamuni Buddha, and consequently indestructible, transcending the changing kalpas. The powerful impact of the long-lived Buddha on the world itself is a significant model for Nichiren, which has allowed and encouraged Nichiren Buddhism to become one of the forms of Buddhism most concerned and engaged with this world, including social issues.