Shingon Buddhism in the context of "Kōzan-ji"

Buddhism was first established in Japan in the 6th century CE. Most of the Japanese Buddhists belong to new schools of Buddhism which were established in the Kamakura period (1185－1333). During the Edo period (1603–1868), Buddhism was controlled by the feudal Shogunate. The Meiji period (1868–1912) saw a strong response against Buddhism, with persecution and a forced separation between Buddhism and Shinto (Shinbutsu bunri).

The largest sects of Japanese Buddhism are Pure Land Buddhism with 22 million believers, followed by Nichiren Buddhism with 10 million believers, Shingon Buddhism with 5.4 million, Zen Buddhism with 5.3 million, Tendai Buddhism with 2.8 million, and only about 700,000 for the six old schools established in the Nara period (710－794).

Shingon Risshū (真言律宗; "Shingon-Vinaya School") is a sect of Japanese Buddhism that integrates the pratimoksha rules, the ordination precepts of Early Buddhism (also called Root Buddhism), and the samaya rules of Vajrayana, all grounded in Shingon Buddhism's esoteric doctrine. It is noted for reviving the spirit of the Risshū sect, one of the Six Schools of Nara Buddhism (南都六宗).

The sect emphasizes adherence to the vinaya—the Buddhist monastic discipline—more than traditional Shingon Buddhism, while retaining tantric practices. Its home temple is Saidaiji Temple in Nara City.

A vajrācārya (vajra + acharya, Tibetan: རྡོ་རྗེ་སློབ་དཔོན་, dorje lopön, Wyl. rdo rje slob dpon, Chinese: 金剛阿闍梨, pinyin: jīngāng āshélì; rōmanji: kongō ajari) (alternatively, Chinese: 金剛上師, pinyin: jīngāng shàngshī) is a Vajrayana Buddhist master, guru or priest. It is a general term for a tantric master in Vajrayana and Mahayana Buddhist traditions, including Tibetan Buddhism, Chinese Esoteric Buddhism, Chan Buddhism, Shingon, Bhutanese Buddhism, Newar Buddhism.

Chinese Esoteric Buddhism refers to traditions of Tantra and Esoteric Buddhism that have flourished among the Chinese people. The Tantric masters Śubhakarasiṃha, Vajrabodhi and Amoghavajra, established the Esoteric Buddhist Zhenyan (Chinese: 真言, "true word", "mantra") tradition from 716 to 720 during the reign of Emperor Xuanzong of Tang. It employed mandalas, mantras, mudras, abhiṣekas, and deity yoga. The Zhenyan tradition was transported to Japan as Tendai and Shingon Buddhism by Saichō and Kūkai, as well as influencing Korean Buddhism and Vietnamese Buddhism. The Song dynasty (960–1279) saw a second diffusion of Esoteric texts. Esoteric Buddhist practices continued to have an influence into the late imperial period and Tibetan Buddhism was also influential during the Yuan dynasty period and beyond. In the Ming dynasty (1368–1644) through to the modern period, esoteric practices and teachings became absorbed and merged with the other Chinese Buddhist traditions to a large extent.

In Chinese these traditions are also termed Mìjiào (Chinese: 密教; Esoteric Teaching), Mìzōng (密宗; "Esoteric Tradition") or Tángmì (唐密; "Tang (Dynasty) Esoterica").

Tendai (天台宗, Tendai-shū), also known as the Tendai Dharma Flower School (天台法華宗, Tendai hokke shū, sometimes just Hokkeshū), is a Mahāyāna Buddhist tradition with significant esoteric elements that was officially established in Japan in 806 by the Japanese monk Saichō. The Tendai school, which has been based on Mount Hiei since its inception, rose to prominence during the Heian period (794–1185). It gradually eclipsed the powerful Hossō school and competed with the rival Shingon school to become the most influential sect at the Imperial court.

By the Kamakura period (1185–1333), Tendai had become one of the dominant forms of Japanese Buddhism, with numerous temples and vast landholdings. During the Kamakura period, various monks left Tendai to found new Buddhist schools such as Jōdo-shū, Jōdo Shinshū, Nichiren-shū and Sōtō Zen. The destruction of the head temple of Enryaku-ji by Oda Nobunaga in 1571, as well as the geographic shift of the capital away from Kyoto to Edo, ended Tendai's dominance, though it remained influential.

Kangiten or Kankiten (Japanese: 歓喜天, "god of bliss"; Sanskrit (IAST): Nandikeśvara), also known as Binayaka (毘那夜迦; Skt. Vināyaka), Ganabachi (誐那鉢底, alternatively Ganahachi or Ganahattei; Skt. Gaṇapati), or more commonly, Shōten or Shōden (聖天, lit. "sacred god" or "noble god"), is a deva (ten) venerated mainly in the Shingon and Tendai schools of Japanese Buddhism.

Although Kangiten (Shōten) in the beginning was (at least at first) negatively portrayed as the creator of obstacles and the leader of a class of malignant demons who obstructed Buddhist practice called vinayakas, though later tradition made an attempt to distinguish between the vinayakas and their lord, who became seen as a manifestation of the bodhisattva Avalokiteshvara (Kannon in Japanese) and/or the buddha Vairochana.