The ‘esoteric’ school of Japanese Buddhism (see Esoteric Buddhism) founded by Kūkai (774–834). Kūkai had become convinced that esoteric practice, which bypassed the necessity of strenuous exertions in religious practice by providing students a means for experiencing directly their own inherent Buddhahood, was the highest form of Buddhism. Thus, the practices of this school centred exclusively on an esoteric curriculum and the student took a particular master as his guru. This master oversaw the abhiṣeka.or initiation ritual, in which the student stood over a maṇḍala.a sacred map of the cosmos that associated various Buddhas andBodhisattvas with certain quarters and directions. By dropping a flower onto the maṇḍala, the student associated himself with and received the protection and empowerment (abhiṣeka) of a particular Buddha or Bodhisattva. After this, the student would engage in ritual visualizations of this Buddha or Bodhisattva, constructing an eidetic mental image of the Buddha in as much detail as possible, realizing that this represented a manifestation of the inherent Buddhahood of his own mind. Such rituals involved the whole person, an ideal reinforced by its use of acts of body, speech, mind (i.e. mudrās or hand gestures, and proper posture; mantras or magical utterances; and the visualization itself). This was considered superior to ‘exoteric’ or conventional practices because, rather than involving the student in a long, slow ascent towards purification and enlightenment (bodhi), it allowed the student to ‘try on’ the role of enlightened being from the outset, thus making possible the attainment, or rather the manifestation, of Buddhahood in a single lifetime. In addition to practices such as those described above, which were directly intended for the student's own enlightenment, esoteric Buddhism from its inception in India also held out the promise of this-worldly benefits for practitioners: invulnerability to weapons, immunity from accidents, ability to heal and make rain, and the like. The Shingon school, even during Kūkai's lifetime, attracted patronage by deploying rituals for these purposes on behalf of paying clients from the royal family and aristocracy. At times, the school concentrated almost exclusively on such lucrative rituals; such periods are generally accounted as times of decline for the school.
Shingon was never the only school of esoteric Buddhism in Japan. From the outset, it competed with the Tendai school, whose form of esoteric practice came to be known as taimitsu, and had its own rituals, scriptures, and was balanced with a complete programme of exoteric teaching and practice that tended to keep it more grounded in Buddhist goals and values. The Shingon form of esoteric practice, called tōmitsu, distinguishes itself by its reliance on two difference maṇḍalas, which, while different, are both affirmed as representing the sacred cosmos. However, Shingon has never enjoyed a great deal of institutional or ritual unity. At the time of Kūkai's death, three different temples all had credible claims to leadership in the school, and disputes over preeminence became quite heated. Also, over the years, Shingon practice has subdivided as styles (Jap., ryū) developed. Eventually, there were more than 36 such styles, generally associated with a particular temple or lineage of masters and students. See also Chen-yen tsung.