Buddhism in Japan began teaching devotion to the "Lotus Sutra". Eventually, his disciples formed their own school of Nichiren Buddhism, which includes various sects that have their own interpretations of Nichiren's teachings. Nichiren Buddhism established the foundation of Japanese Buddhism in the thirteenth century. The school is known for its sociopolitical activism and looks to reform society through faith. In the Muromachi period, Zen, particularly the Rinzai school, obtained the help of the Ashikaga shogunate and the Emperor of Japan, and accomplished considerable development. After the Sengoku period of war, Japan was re-united in the Azuchi–Momoyama period. This decreased the power of Buddhism,
Buddhism in Japan particular, represents almost every strand of Buddhist teachings and practices. However, in comparison to Chinese or Korean Buddhist schools that are generally more united and less sectarian in their groupings, Buddhist denominations in Japan have developed into independent sects with autonomous organizations that have differing emphases on the doctrine and separate lay followings." (Authors: Kawananami, Partridg, and Woodhead page 82.)]In the post-Meiji, pre-WWII period, there were officially 13 schools and 56 branches () of traditional Buddhism (i.e., those not established in modern times). The official schools included three from the Nara period, two from the Heian period (Tendai and Shingon),