QUESTION: In what age will the secret dharmas entrusted to Superior Practice and other bodhisattvas called out from the underground be spread?

ANSWER: The 23rd chapter, “The Previous Life of the Medicine King Bodhisattva” of the Lotus Sūtra, fascicle 7, preaches: “Propagate this chapter throughout this world during the last 500-year period after My extinction lest it should be lost.” Reading this passage in the sūtra respectfully, I see that the time for the secret dharmas to spread will be after the passage of the 2,000-year periods of the Ages of the True Dharma and the Semblance Dharma, namely during the fifth 500-year period after the death of the Buddha, which coincides with the beginning of the Latter Age of Degeneration, when it is believed that strife becomes rampant with Buddhism progressively declining to extinction.

Sandai Hiho Honjo-ji, The Transmission of the Three Great Secret Dharmas, Writings of Nichiren Shōnin, Doctrine 2, Page 287-288