The Three Treasurers of Buddhism are the Buddha, the Law and the Priest.
The Three Treasures of True Buddhism are
Nichiren Daishonin, the Gohonzon and
Nikko Shonin.
THE BUDDHA
Buddhism is a teaching preached by an enlightened one or a Buddha. In Nichiren Shoshu Buddhism Nichiren Daishonin (1222-1282) is believed to be the eternal Buddha and true Buddha of the Latter Day, for his was the mission to reveal the original cause of enlightenment of all Buddhas, which was his own life of Namu-myoho-renge-kyo, and to make the enlightenment of all living things possible. Nichiren Daishonin is therefore the Treasure of the Buddha in Nichiren Shoshu Buddhism.
THE LAW
The True Law is Namu-myoho-renge-kyo, the source of ichinen sanzen. The fusion of the True Law with the eternal life of the Buddha is manifested in the Gohonzon. (This is the oneness of person and the Law.) Down the center of Gohonzon is written Namu-myoho-renge-kyo and beneath that, in linear symmetry, is the Daishonin's signature and seal. In "Letter to Kyo", Nichiren Daishonin wrote, "I, Nichiren, have inscribed my life in sumi, so believe in the Gohonzon with your whole heart." In Nichiren Shoshu the Gohonzon represents the Treasure of the Law.
THE PRIEST
Specifically, Nikko Shonin (1246-1333), Nichiren Daishonin's closest disciple, represents the Treasure of the Priest. However, it is not the person or personality of Nikko Shonin that is the third treasure. It is Nikko Shonin who embraced, kept and transmitted all of Nichiren Daishonin's teachings accurately, both in word and spirit, that is revered as the third treasure. Therefore, essential to the Treasure of the Priest is the adherence to the complete and truthful teaching of the Daishonin.
Generally speaking, all successive high priests who keep the Daishonin's teachings as Nikko Shonin did are the Treasure of the Priest, as are all priests and lay believers who likewise practice and keep the faith.