Our Compassionate Father, the Greatly Awakened and World Honored One, appeared in this world in Central India when the life span of human beings was 100 years and spent His life preaching the holy teachings for all living beings. All living beings during the lifetime of the Buddha were closely related to the Buddha due to the accumulated merit of their virtuous deeds in the past. Therefore, they were able to attain Buddhahood during the lifetime of the Buddha. For the sake of those living after the passing of the Buddha, however, the Buddha expressed His 84,000 holy teachings in writing, giving Hinayāna sūtras to Honorable Kāśyapa and Mahāyāna sūtras including the Lotus Sūtra and Nirvana Sūtra to Bodhisattva Mañjuśrī to be spread among living beings after the passing of the Buddha.
However, the five characters of Myō, Hō, Ren, Ge, and Kyō, which are the essence of the 84,000 holy teachings and the primary object of the Lotus Sūtra, were entrusted neither to Kāśyapa nor Ānanda. They were not given to great bodhisattvas such as Mañjuśrī, Samantabhadra, Avalokiteśvara, Maitreya, Earth Repository, or Nāgārjuna. They were all anxious to receive the five characters from the Buddha but their request was denied. Śākyamuni Buddha in a Stupa decorated with the seven treasures instead called out an elder named Superior Practice Bodhisattva from the bottom of the earth and gave him the five characters of Myō, Hō, Ren, Ge, and Kyō before the Buddha of Many Treasures and Buddhas in manifestation coming from all the worlds throughout the universe.
Why did Śākyamuni Buddha do this? All living beings after the passing of the Buddha are considered the same dear children to Śākyamuni Buddha. According to the general practice of physicians, the Buddha prescribed medicine suitable to the condition of the patient. Therefore, the Buddha directed Kāśyapa, Ānanda, and others to prescribe the medicine of Hinayāna sūtras to all living beings during the first half (500 years) of the Age of the True Dharma. For the second half of the Age of the True Dharma such bodhisattvas as Mañjuśrī, Maitreya, Nāgārjuna and Vasubandhu, were directed to prescribe such Mahāyāna sūtras as the Flower Garland Sūtra, the Great Sun Buddha Sūtra, and the Wisdom Sūtra for all living beings. For the Age of the Semblance Dharma, the ten-century period beginning in the 1,000th year after the passing of the Buddha, Medicine King Bodhisattva and others were ordered to prescribe the Lotus Sūtra with the exception of the daimoku for all living beings.
However, in the Latter Age of Degeneration beginning 2,000 years after the passing of the Buddha, the Hinayāna and Mahāyāna sutras given to Kāśyapa, Ānanda, Mañjuśrī, Maitreya, Medicine King, Avalokiteśvara and others were no longer useful as medicine for living beings. It is because they were no longer effective as cures for the severe ailments of living beings. While the Buddha considered what to do about this, Superior Practice Bodhisattva emerged from the earth. The Buddha then ordered the bodhisattva to give the five characters of Myō, Hō, Ren, Ge, and Kyō to all living beings throughout the Jambudvīpa.
Takahashi Nyūdō-dono Gohenji, A Response to Lay Priest Lord Takahashi, Writings of Nichiren Shōnin, Volume 7, Followers II, Pages 74-75