Buddhism in Japan. The dominant religious tradition of Japan, Buddhism first entered Japan c.5th or 6th cent. CE, from the Chinese mainland (traditionally in 538 from Korea). Initially, a few powerful clans opposed the new religion, but by the end of 6th cent. the emperor himself embraced Buddhism, and it received the devotion and patronage of the highest levels of Japanese society. Shōtoku Taishi or Prince Shōtoku (574–622) was instrumental in consolidating Buddhism in Japan (see NARA BUDDHISM).

Japan's schools of Buddhism are generally categorized according to the historical period in which they emerged: Nara period (710–84), Heian period (794–1185), and Kamakura period (1185–1333). During these periods the Japanese assimilated the content of Buddhism, while also adapting it to their own religious sensibilities. Nara Buddhism consisted of six schools which were virtual transplants from China: Hossō, Kusha, Sanron, Jōjitsu, Kegon (Chin., Hua-yen), and Ritsu. These were not separate sectarian organizations but mostly philosophies of Buddhism studied side by side in the major temples of the ancient capital of Nara.

Heian Buddhism was comprised of two schools: Tendai (Chin., T'ien-t'ai) founded by Saichō (767–822) and Shingon founded by Kūkai (774–835).

Japanese Buddhism reached its height in the Kamakura period with the Pure Land schools of Hōnen (1133–1212), Shinran (1173–1262), and Ippen (1239–89); the Zen schools of Eisai (1141–1215), known as Rinzai (Chin., Linchi), and Dōgen (1200–53), known as Sōtō (Chin., Ts'ao-tung); and the Nichiren school of Nichiren (1222–82). Each of these was strongly sectarian in outlook, emphasizing one specific practice to the exclusion of others. Amalgamation with Shinto, pursuit of worldly benefits, rigorous observance of vows, celibacy, study and meditation, clerical rights all became less important, and simple practices aimed at personal salvation emerged as the central concern. These new forms of Buddhism appealed to ordinary believers who could not meet up to the requirements of the earlier schools. Hence, Kamakura Buddhism became the religion of the masses, and it eventually overshadowed the Nara and Heian schools. To this day the Kamakura schools claim the vast majority of Japan's population as adherents.