Kūkai was born in 774 in the present-day Zentsū-ji precincts on the island
of Shikoku. As a boy named “Mao” born in an aristocratic family, he studied
Chinese classics and Confucianism by his maternal uncle, a Confucian scholar. At the age of 18, he is said to have entered the state university at the then-capital Nagaoka but was soon disillusioned with the education of the university where most of the graduates moved on to become bureaucrats. He dropped out of the university to devote himself to various forms of esoteric practices in the natural setting of the mountains. In the meantime, Kūkai was introduced to an esoteric meditative practice called the Kokûzôgumonji-h which involved the recitation of a mantra a million times in 100 days and was supposed to endow the practitioner with miraculous powers of memory and understanding. A few years later at the age of 24, Kukai wrote Sango-shiiki (Indications to the Three Teachings), a work in which he attempts to reveal the superiority of Buddhism by evaluating the respective contributions of Confucianism, Taoism, and Buddhism. Despite his recognition of the superiority of Buddhism, Kukai was not satisfied with the traditional sects represented by the Nara schools, which he had studied. It appears that between the ages of 24 and 31, he wandered through its various mountains and sacred sites, practicing asceticism as a private mendicant monk. During this period, Kūkai happened to encounter the Mahavairocana sūtra but as Kūkai could find no one who could elucidate the text for him, he resolved to go to China to study the text there. In April 804, he set out for China in the company of the ambassador to the T’ang court, Fujiwara-no Kadonomaro. He travelled to Chang-an (=present X’ian), the capital of the T’ang dynasty. During his sojourn for about 2 years, he studied Indian Buddhism, Hindu teachings, and Sanskrit with two Indian monks. But more significantly, he met Master Huiguo (746-805), the seventh patriarch of Chen-yen (=Shingon) Buddhism at Qinglong Monastery in Chang-an. Whereas Kūkai had expected to spend 20 years studying in China, he received the final initiation, surprisingly, in a few short months and then became the 8th patriarch of the Chen-en esoteric lineage combining Vajraśekhara Sûtra with Mahâvairocana Sûtra.
Kûkai returned to Japan in 806 at the age of 33. He arrived in Kyushu with a voluminous amount of sûtras, collections of mandala paintings, books, ritual paraphernalia and etc. However, he was not permitted to enter the capital due to political unrest and was obliged to remain in Kyushu for another three years. In 809, the new Emperor Saga ordered Kûkai to move to the new capital of Kyoto to reside at Takaosan-ji, the center of the Kyoto Buddhist world. Under the patronage of Emperor Saga, Kûkai was appointed over the years to various administrative positions of several important official temples. This allowed him to perform a various forms of esoteric ceremonies, hence gaining official recognition for the efficacy of esoteric Buddhism and preparing the rise of Buddhism as an ideological force in medieval Japan. In 816, after obtaining sanction from Emperor Saga, Kûkai began building a monastic center in Mt. Kôya, and there he passed away in 835 at the age of 62. In 921, he posthumously received from Emperor Daigo, the honorific title, “Kôbô Daishi “ (=“Great Teacher Who Spread the Dharma”). He is also renowned for his excellent talents as a teacher, civil engineer, poet, calligrapher and etc. Kobo Daishi is one of Japan’s most famous Buddhist saints beloved by the people regardless of sectarian differences. Among the followers of Shingon sect of Buddhism, Kobo Daishi is still believed to have not just died but entered into an eternal meditation for salvation of people.