Most religious founders leave behind writings, and different schools that grow from those writings can at least agree on what the founder wrote, even while disagreeing about what it means. Nichiren left something else too, according to one of his own lineages: a specific physical object, inscribed once, meant to outlast every argument about how to read him.
Taisekiji, the head temple of Nichiren Shoshu near Mount Fuji, holds a large wooden mandala it calls the Dai Gohonzon and dates to a single day, the twelfth of the tenth month in the traditional calendar, in the year 1279. Nichiren Shoshu doctrine holds that Nichiren inscribed it himself, in the aftermath of a persecution earlier that year in which peasant believers were arrested and three executed for their faith, and that he meant it as the ultimate object of devotion for every future believer, not merely for the community immediately around him.
What makes the object unusual is not the claim but what happens to the claim outside Taisekiji's own walls. Nichiren Buddhism split into several schools within decades of Nichiren's death, all tracing back to the same founder and the same writings, and none of the others share this specific mandala or its story. A scholar examining the historical record calls the Taisekiji tradition just that, a tradition specific to one school, not a fact the wider Nichiren world accepts as settled. The mandala does not resolve the disagreement among Nichiren's heirs. It is, itself, one of the things they disagree about.