Kūkai (27 July 774 – 22 April 835), also known posthumously as Kōbō Daishi, was a Japanese Buddhist monk, calligrapher, and poet who founded the Esoteric Shingon school of Buddhism. He travelled to China, where he studied Tangmi (Chinese Vajrayāna Buddhism) under the monk Huiguo. Upon returning to Japan, he founded Shingon—the Japanese branch of Vajrayāna Buddhism. Mount Kōya is a main centre of Shingon

The Thirteen Buddhas (Jūsan Butsu) is a Japanese grouping of Buddha aspects, characteristic to the Shingon tradition of Buddhism. Jūsan Butsu, the 13 Buddhas of the Shingon School, are often found represented together in painted images consisting of 5 Buddhas, 7 Bodhisattvas and Fudō Myōō. All together they represent the chief deities of the Taizōkai (Womb Realm, garbha-kośa-dhātu) and Kongōkai (Diamond Realm, vajra-dhātu) mandalas.

The Mantra of Light, also called the Mantra of the Unfailing Rope Snare, is an important mantra of the Shingon and Kegon schools of Buddhism. In its syllables, the entire power of the omnipresent Mahāvairocana (Dainichi Buddha) manifests. Both the Mantra of Light and the Nembutsu were often incorporated by Medieval Buddhists at one time or another, often in the same service.

Mount Kōya (Kōya-san) is a large temple settlement in Wakayama Prefecture, Japan to the south of Osaka. First settled in 819 by the monk Kūkai (774-835), Mount Kōya is primarily known as the world headquarters of the Kōyasan Shingon sect of Japanese Buddhism. Mount Kōya is also a common starting point to the Shikoku Pilgrimage (Shikoku Junrei) associated with Kūkai. Home of 117 temples.

Acala ("The Immovable") is a wrathful deity and Dharmapāla (protector of the Dharma) prominent in Vajrayāna Buddhism and East Asian Buddhism. Currently it is most popular in Japanese Buddhism as Fudō Myōō: It is believed this figure was introduced in Japan by the founder of Shingon Buddhism Kūkai, who brought the teachings of Esoteric Buddhism from China in 805. Fudō Myōō is popular in Japan.