[A]nother form of honzon possibly adopted during Nichiren’s lifetime is known as the “one Buddha and four attendants” (isson shishi). It probably derives from passages in Nichiren’s writings such as the following, in a letter to his follower Toki Jōnin (1216-1299), dated 1279:

You say in your letter: “I have heard before that an object of worship should be made of the Lord Śākyamuni of the origin teaching, who attained enlightenment in the remotest past, and that, as attendants, [images] should be made of the four leaders of the bodhisattvas emerged from the earth who are his original disciples. But when [is this object of worship to be established] as I have heard?”

… Now in the Final Dharma age, in accordance with the Buddha’s golden words, [an object of worship] should be made of the original Buddha and his original attendants.

And in fact, Toki Jōnin’s index of the writings, icons, and ritual implements preserved at the temple he established after Nichiren’s death includes “a standing image of Śākyamuni and also the four bodhisattvas (in a small shrine).” The presence of the four bodhisattvas signals that the central icon is the original or eternal, rather than the merely historical, Śākyamuni. The “one Buddha and four attendants” came into fairly widespread use among Nichiren’s followers as a honzon almost immediately after his death. There was also a more complex configuration consisting of the two Buddhas, Śākyamuni, and Many Jewels, seated together in the jeweled stūpa and flanked by the four bodhisattvas (ittō ryōson shishi). The earliest attested grouping was made by Jōgyōin Nichiyū (1298-1374) of the Nakayama lineage in 1335. (Page 275)