Nichiren (1222 to 1282) himself made increasingly direct claims about his own religious status across his life's writings, moving from presenting himself as a devoted expounder of the Lotus Sutra toward statements, especially in letters written during and after his exiles, that identify his own person with the Buddha of the Latter Day of the Law, the degenerate final age Buddhist cosmology holds the historical Buddha's own teaching to be entering. Nichiren Shoshu, the school descending from Nichiren's disciple Nikko, developed this claim into settled doctrine through the systematic writings of the eighteenth century priest Nichikan, who argued from Nichiren's own letters, collected as the Gosho, that Nichiren was not merely a teacher expounding the Lotus Sutra's truth but the very Buddha the Lotus Sutra itself foretold would appear to save beings in the Latter Day, a status Nichikan's doctrine distinguishes from the historical Buddha Shakyamuni's own teaching authority, which Nichiren Shoshu doctrine holds to have already exhausted its saving power for the current age. The claim rests specifically on Nichiren's own writings rather than on later invention, though the school's most systematic doctrinal statement of it came generations after Nichiren's death, in Nichikan's formal argument for reading the Gosho's more suggestive passages as a direct, intended self-identification rather than as rhetorical emphasis.