[T]he underground bodhisattvas of chapter 15 have
special significance for Nichiren: “The countless bodhisattvas who had sprung up from underground were disciples of Lord Śākyamuni Buddha ever since the time He had first resolved to seek Buddhahood.” Although they had not visited Śākyamuni throughout his awakening under the bodhi tree and his expounding of the lesser sutras, since making their vow in the Lotus Sutra they are especially promised to appear in the mappō times, which Nichiren believed had already arrived.

Thus the underground bodhisattvas are greater for Nichiren than the familiar disciples, and even greater than the celebrated archetypal bodhisattvas such as Samantabhadra, Mañjuśrī, and Maitreya. “The numerous great bodhisattvas, who had been guided by the Original Buddha in the past, sprang out of the earth of the whole world, according to [chapter 15]. They looked incomparably superior to Bodhisattva Fugen (Samantabhadra) and Mañjuśrī, who had been regarded as ranking disciples. Even Bodhisattva Maitreya, successor to Śākyamuni Buddha, did not know who they were, not to speak of other bodhisattvas.”

Nichiren sees the underground bodhisattvas as the model for those who carry out the teaching of the enduring Śākyamuni in current conditions. And Nichiren himself personally identified with these underground bodhisattvas: “When these four great bodhisattvas, leaders of those who sprung up from underground, spread this sutra through aggressive means of propagation, they would appear as wise kings reproaching ignorant kings.” Practicing a persuasive means of propagation, they would be monks upholding and spreading the true dharma. In the final age of degenerate Dharma that Nichiren regarded as having arrived in Kamakura-period Japan, the imperative of proclaiming and propagating the Lotus Sutra teaching gained a new urgency. It was embodied for Nichiren by the enduring Śākyamuni and especially conveyed to the myriad beings by the underground bodhisattvas.

Nichiren states that the “Eternal” Śākyamuni Buddha “exists forever throughout the past, present, and future. All those who receive His guidance are one with the Eternal Buddha.” He goes on to state that the Śākyamuni Buddha of the sixteenth chapter differs from the earlier Śākyamuni Buddha of provisional sutras, and advocates that the enduring Śākyamuni, and his image, be the new object of veneration in the current Age of Decline (mappō), replacing images of the Śākyamuni who expounded the pre-Lotus sutras.

Nichiren strongly emphasizes the end of chapter 15 and chapter 16. This is the part of the sutra that “Nichiren judges to be almost exclusively representative of the meaning of the entire scripture.” Lucia Dolce describes the difference in Nichiren’s interpretation of the sutra from Zhiyi’s as Nichiren seeing the long-lived Śākyamuni Buddha as the single ultimate buddha encompassing all others. Whereas Zhiyi emphasized the sambhogakāya, or recompense body, and valued many other particular buddhas, Nichiren declares “that all Buddhas enlightened in the past are emanations of Śākyamuni” of chapter 16, based on the events of chapter 11, in which emanations arrive to witness the other Buddha in his stūpa. For Nichiren, this long-lived Buddha includes all three bodies, including the manifested transformation body, nirmāṇakāya, and even Vairocana, the reality body or dharmakāya: “Only the [chapter 16] Śākyamuni who reveals his enlightenment in the past embodies the true Mahāyāna Buddha.”

Nichiren’s view of temporality is determined by this story, as his emphasis on it “corresponds to the dilation of the temporal dimension expressed in those chapters, that is, the distant past in which Śākyamuni obtained his original enlightenment. Nichiren absolutizes this original moment and makes it the only significant time and relates it to the existence of humanity in a certain time and place.” He does not describe this Buddha as literally eternal, but “uses the expression ‘without beginning and without end,’ ” signifying “an existence not subject to temporal limitations.” Because this limitlessness includes the transformation body, “the Buddha has always abided in this world and … his soteriological activity has been constant since the original time.” [Dolce]

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.