Kūkai in the context of Mount Kōya

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").

The Shikoku Pilgrimage (四国遍路, Shikoku Henro) or Shikoku Junrei (四国巡礼) is a multi-site pilgrimage of 88 temples associated with the Buddhist monk Kūkai (Kōbō Daishi) on the island of Shikoku, Japan. A popular and distinctive feature of the island's cultural landscape, and with a long history, large numbers of pilgrims, known as henro (遍路), still undertake the journey for a variety of ascetic, pious, and tourism-related purposes. The pilgrimage is traditionally completed on foot, but modern pilgrims use cars, taxis, buses, bicycles, or motorcycles, and often augment their travels with public transportation. The standard walking course is approximately 1,200 kilometres (750 mi) long and can take anywhere from 30 to 60 days to complete.

In addition to the 88 "official" temples of the pilgrimage, there are 20 bekkaku (別格) temples, which are officially associated with the Shikoku Pilgrimage (and hundreds more bangai (番外) temples, simply meaning "outside the numbers", which are not considered part of the official 88). To complete the pilgrimage, it is not necessary to visit the temples in order; in some cases, pilgrims complete the journey in reverse, a practice known as gyaku-uchi (逆うち).

Shingon (真言宗, Shingon-shū; "True Word/Mantra School") is one of the major schools of Buddhism in Japan and one of the few surviving Vajrayana lineages in East Asian Buddhism. It is a form of Japanese Esoteric Buddhism and is sometimes called "Tōmitsu" (東密 lit. "Esoteric [Buddhism] of Tō-ji"). The word shingon is the Japanese reading of the Chinese word 真言 (zhēnyán), which is the translation of the Sanskrit word mantra.

The Zhenyan lineage was founded in China (c. 7th–8th centuries) by Indian vajrācāryas (esoteric masters) like Śubhakarasiṃha, Vajrabodhi and Amoghavajra. These esoteric teachings would later flourish in Japan under the auspices of a Buddhist monk named Kūkai (空海, 774–835), who traveled to Tang China and received these esoteric transmissions from a Chinese master named Huiguo (746–805). Kūkai established his tradition at Mount Kōya (in Wakayama Prefecture), which remains the central pilgrimage center of Shingon Buddhism.