Nichiren (日蓮; 16 February 1222 – 13 October 1282), born as Zennichimaro (善日麿), was a Japanese Buddhist priest who lived during the Kamakura period (1185–1333). Nichiren is known for his sole devotion to the Lotus Sutra, asserting that it was Shakyamuni Buddha's ultimate teachings and was the exclusive method to attain enlightenment. Nichiren believed that the Lotus Sutra contained the essence of all of Shakyamuni Buddha's teachings related to the laws of causality, karma, without any distinction to enlightenment. His interpretation of the Lotus Sutra centers on the emphasis of its 16th chapter, The Life Span of the Thus Come One, where he asserts his revelation that the chanting of Nam Myōhō Renge Kyō is the superior practice of today's age (Mappō).
Nichiren further justifies this practice of chanting Nam Myōhō Renge Kyō by attributing the natural and social calamities of his time to the inability of the Pure Land, Zen, Shingon, Ritsu, and Tendai schools to supernaturally protect Japan. Nichiren gained the attention of Japan's ruling Hōjō clan when his two Lotus Sutra-based predictions of foreign invasion and political strife were seemingly actualized by the Mongol invasions of Japan and an attempted coup within the Hōjō clan. The religious remonstration where he stated these two predictions, titled the Risshō Ankoku Ron (立正安国論) (On Establishing the Correct Teaching for the Security of the Land), considered by Japanese historians to be a literary classic illustrating the apprehensions of that period.
While all Nichiren Buddhist schools regard him as a reincarnation of the Visistacaritra or Jōgyō (上行), the lineages from Nikko Shonin proclaim Nichiren as the "Original Buddha" from infinite aeons ago, addressing him the title of Dai-Shonin (Kanji: 大聖人, English: Great Sage) as well as "True Buddha of the Latter Day of the Law" as taught Three Ages of Buddhism.
Today, Nichiren Buddhism includes traditional schools such as Nichiren Shōshū, the Nichiren Shū confederation of schools, and modern lay movements such Kenshokai, Shoshinkai, Soka Gakkai, Risshō Kōsei Kai, and Honmon Butsuryū Shū and various others each claiming their own interpretations of Nichiren's teachings. The fundamental practice shared by all of them is the chanting of Nam Myōhō Renge Kyō. SOURCE: Wikipedia