According to Nichiren, in the second section of the Lotus Sutra Śākyamuni speaks of this Sahā world as the original land, a pure Buddha realm compared to which the other lands of the ten directions are mere conventional worlds. In Chih-i’s exegesis, the “original land” is the land in which the original Buddha attained enlightenment, therefore the realm of only one type of Buddha. This “Sahā world of the original time” contrasts with the Sahā world where human beings live, which retains the characteristics of a “trace-land.” For Nichiren, on the contrary, there is only one Sahā world. Vulture Peak, the place where the Lotus Sutra is taught, represents both this world of ours and the most perfect world, the only possible “paradise.” There is no other reality, neither for humanity, nor for the Buddha. Whereas Chih-i apparently believed in the Western paradise of Amitābha and hoped to reach it after his death, Nichiren considered the assembly on Vulture Peak a symbol of those who, having received the teachings of the Lotus Sutra, are able to transform our Sahā world into a “resplendent land.” (See this blog post.)

In Nichiren’s hermeneutics the original land thus equals the human world. Since the world where humans live is also the original world in which the Buddha attained buddhahood, phenomenal reality becomes the ground of the most complete enlightenment, which opens to ultimate reality. This enlightenment of the Buddha in the remote past justifies the buddhahood of all beings of this world: Nichiren insists that the śrāvakas and pratyekabuddhas who are promised enlightenment in the first section of the Lotus Sutra could never in fact attain it if the original enlightenment of the Buddha described in chapter 16 had not occurred.
A Buddhist Kaleidoscope; Lucia Dolce, Between Duration and Eternity: Hermeneutics of the ‘Ancient Buddha’ of the Lotus Sutra in Chih-i and Nichiren, Page 232-233