Focus on this artwork and discuss the Claims of origin.
The Nichiren Shōshū sect claims that Nichiren inscribed the Dai Gohonzon on 12 October 1279 (Japanese: Ko-an). Nichiren Shōshū adherents cite the following passage in Nichiren's "On Persecutions Befalling the Sage" addressed to the Buddhist Samurai warrior Shijo Nakatsukasa Saburō Saemon—no—jō Yorimoto (四条中務三郎左衛門尉頼基, 1230–1296), which they assert supports the origin story of the image: "...Shakyamuni Buddha fulfilled the purpose of his advent in a little over 40 years, — the Great Teacher Zhiyi took about 30 years — and the Great Teacher Saichō, some 20 years. I have spoken repeatedly of the indescribable persecutions they suffered during those years. 
For myself, Nichiren, it took 27 years, and the great persecutions I faced during this period are well known to you all."
According to the sect, the creation of the Dai Gohonzon image is the ultimate purpose of Nichiren's entrance into the Sahā world of humans. Furthermore, they claim that this particular Gohonzon was inscribed so that all people in the Third Age of Buddhism can attain Buddhahood in their present life existence (Sokushin Jobutsu). Nikko Shonin's last will and testament document to Nichimoku Shonin, "Articles to be Observed After the Passing of Nikko" ("Nikko ato jojo no koto"), states "...The Dai-Gohonzon of the second year of Kō`an (1279), which Nikko inherited, is hereby bequeathed to Nichimoku." Two original transfer documents exist written by Nikko Shonin.  Of the two, the first document is a draft written in the second year of Gentoku (1330).  The second is the actual transfer document itself, dated the first year of Shoukei (1332). Both documents are signed by Nikko Shonin.  The signatures on these documents have been determined to be consistent with Nikko Shonin's signature from the period in his life.
Additionally, the third High Priest, Nichimoku Shonin, stated "...The Dai-Gohonzon, which was entrusted upon the person of Nikko, is the plank Gohonzon. It is now here at this temple (Taisekiji)." From documents written by Nikko Shonin and Nichimoku Shonin, the Dai-Gohonzon was transferred between the successive high priests of Nichiren Shoshu. The sect further claims that the Dai Gohonzon may only be publicly enshrined for widespread access when Japan converts to this religion, including the Emperor of Japan who is charged the formal task to decree that a national shrine for the image can be built at the foot of Mount Fuji.The fourteenth High Priest, Nisshu Shonin, stated in his writing "On Articles to Be Observed after the Passing of Nikko" ("Nikko ato jojo no koto jisho"), "...The Gohonzon concerns the transfer matters of Taiseki-ji, which denotes the exclusive transfer from one high priest to another. The Dai Gohonzon of the High Sanctuary of the Essential Teaching, which Nikko Shonin inherited from the Daishonin and transferred to Nichimoku Shonin in the era of Shoan, is exactly and changelessly the whole entity of the transfer through the Nichiren–Nikko–Nichimoku lineage in the Latter Day of the Law."The Nichiren Shoshu sect teaches that the image is inherited from one singular High Priest to the next living incumbent. Accordingly, the sect teaches that there are two kinds of transmission of its Dharma essence: "specific transmission," referred to by the sect as the "Heritage of the Entity of the Law," which claims the Dai Gohonzon image is bestowed and entrusted to each of the successive High Priests passed on by one person at a given time; and "general transmission," referred to by the sect as "Heritage of Faith" and pertaining to both disciples and believers who chant and follow closely its doctrines. Accordingly, the priesthood of the sect claims that due to the present incompleteness of the altar of the Dai Gohonzon, it is not enshrined with Japanese Shikimi evergreen plants nor Taiko drums. In addition, they believe that the Dai Gohonzon should not be exposed for public view until kosen-rufu is achieved, primarily referring to Nichiren Shoshu becoming the main religion on the planet.The 26th High Priest, Nichikan Shonin, declared in his treatise "Exegesis on the True Object of Worship" ("Kanjin no honzon-sho mondan") the following regarding the image: "...The Gohonzon of the High Sanctuary of the Essential Teaching, inscribed in the second year of Koan (1279), is the ultimate, the absolute, and the final cause of the Daishonin's advent. It is the greatest among the Three Great Secret Laws and the supreme object of worship in the entire world." Due to this charge of protecting the image, 59th High Priest Nichiko Hori declared the following regarding the matter: "In the early times, this matter (the Dai-Gohonzon) was not publicized within our school nor outside." On 16 September 1972, the 66th High Priest Nittatsu Hosoi Shonin in Hokeiji Temple in Omuta, Fukuoka Prefecture  asserted the authenticity of the wooden image, and cited the procurement of the log from a secluded part of Mount Minobu in response to the claims of external sourcing of the wood by other sects.
Omuta, Fukuoka Zhiyi Taisekiji Saichō Nichiren Shōshū Emperor of Japan log Taiko Taiseki-ji Nikko Shonin Samurai Nichiren Buddhahood kosen-rufu Japanese last will and testament Nichiren Shoshu Sahā Shakyamuni Buddha Nichimoku Mount Fuji Japan Nittatsu Hosoi Dharma Gohonzon Shikimi Third Age of Buddhism