Kobo Daishi, commonly known as "O-Daishi-sama", was born in the year 774 (5th year of the Houki era) during the reign of Emperor Kōnin in Sanuki Province (present-day Kagawa Prefecture). His father was Saeki no Atatagimi and his mother was from the Ato family, and O-Daishi-sama's childhood name was Mao. It is said that the family had a strong faith in Buddhism.

At the age of 15, he accompanied his uncle, Doctor of Literature Atou Otari, to Tokyo, where he studied Chinese classics and history, and at the age of 18, he entered the Department of Chinese Classics (present-day Faculty of Literature) at the University of the capital, where he studied the Chinese classics and Confucianism. The Daishi had a great talent for Chinese poetry, which he further honed during this period.

At that time, universities were Confucian-centered institutions for training officials, which was different from the Master's desire to save people who were suffering. During this time, he learned Buddhist teachings from Nara's Kinso Daitoku and was given the teachings of Kokuzo Gumonji, which marked the beginning of his major transformation. Finally, in 793 (Enryaku 12), at the age of 19, he became a monk at Makio-san Temple in Izumi Province, with Kinso Daitoku as his teacher. His monk name was Kyokai, later changed to Nyoku, and at the age of 22, he received the full precepts at Todaiji Kaidan-in and changed it to Kukai.

After leaving the monk's ... After that, he was inspired by the Mahavairocana Sutra at Kumedera Temple and devoted himself to its study, but as the sutra contained Sanskrit (an ancient Indian language) and was difficult to understand, he decided to travel to China. Thanks to the extraordinary efforts of Kinso Daitoku, on July 6, 804 (23rd year of Enryaku), the Master boarded the first ship of the Japanese envoys to China, with Fujiwara Kadonomaro as the ambassador, and departed from Tanoura Port, Matsuura County, Hizen, on August 10, and was washed ashore on the shores of Fuzhou, arriving in Chang'an, the capital of China, in December of the same year. In this city, he entered the gates of the seventh patriarch, Keika Ajari of Seiryu-ji Temple, who bestowed upon him the great teachings of Esoteric Buddhism in just eight months, bestowing on him the name "Henjo Kongo", and making him the eighth patriarch. Two years later, in 806 (first year of Daido), he returned to Japan and spread Esoteric Shingon Buddhism throughout the country.

On November 15, 812 (Kōnin 3), the Kongokai Ketsuen Kanjō ceremony was held at Mt. Takao. Among the initiations was Dengyo Daishi, which instantly raised the reputation of Kobo Daishi in the Buddhist world and the Imperial Court. Many disciples also gathered around Kobo Daishi. It is said that Shingon Buddhism was established around this time.

In 816 (Kōnin 7), Emperor Saga bestowed Mt. Koya, and in 817 (Kōnin 8), the disciples, accompanied by many craftsmen, climbed the mountain and began the founding of the temple, which is said to be the beginning of Kongobu-ji Temple at Mt. Koya.

In May 821 (Kōnin 12), the Imperial Court appointed Kōbō Daishi as the head of the repair of Mannoike Pond in Sanuki Province. Kōbō Daishi was from Sanuki Province and is said to have studied in China, where he saw and experienced advanced technological civilization, and acquired advanced knowledge and skills in civil engineering. He successfully completed the difficult task of repairing the large reservoir in just three months.

In February 822 (Kōnin 13), he built an ablution training center (Shingon-in) at Todaiji Temple, practiced the Ninno Sutra (a Buddhist sutra for the protection of the nation) at Takaosan-ji Temple, bestowed the Sammaya precepts, which are unique to esoteric Buddhism, on Emperor Heizei and performed the ablution, and there are records that he also performed the ablution on Emperor Saga the following year (Kōnin 14).

In the first month of the year 823 (Kōnin 14), the Imperial Court bestowed To-ji Temple on Kobo Daishi. Since then, it has served as the main training center for the Shingon sect and a base for social activities. He was ordered by the government to have 50 disciple monks permanently reside there, to prohibit monks of other sects from living there, and to devote himself to the study of Esoteric Shingon Buddhism.

In February 824 (Tencho 1), the Daishi prayed for rain at Shinsen-en by imperial decree, and the following month he was appointed Shosozu. In May of the same year (Tencho 4), he performed a rain-praying ceremony at the Imperial Palace and was appointed Daisozu.

Kōbō Daishi wrote many books despite his busy life. The two types of "Fūhoden" (Fuhoden) of Kōbō clarify the lineage and legends of the founders who inherited and passed down orthodox esoteric Buddhism from Dainichi Nyorai to Master Huiguo. He wrote the three Shingon texts "Sokushin Jōbutsugi," "Shoji Jissogi," and "Unjigi," which clarify the theoretical basis of Shingon teachings. His other works include "Bunkyo Hifuron," "Bunpitsu Ganjinsho," "Tenrei Bansho Meigi," "Jujushinron," "Hizo Hoyaku," and his most recent work, "Hannya Shingyo Hiken."

In 828 (Tencho 5), he opened a school called Shugeishuchiin to the east of Toji Temple, which was a very open school with no restrictions on admission based on social status or wealth. However, it was closed after 20 years due to financial and human resource shortages.

While the construction was still ongoing, Daishi entered nirvana on March 21, 835 (Jowa 2), at the age of 62, and attained instantaneous enlightenment. Later, on October 27, 921 (Engi 21), Emperor Daigo bestowed upon him the posthumous title of "Kobo Daishi." Daishi is still by our side at Mount Koya, the training center for Shingon Buddhism. On the Shikoku Pilgrimage, the kongo staff carried by pilgrims represents the two of them traveling together, and Daishi acts as their feet and emotional support as he walks alongside the pilgrims.

Thankfully, in the shade of the rocks on Mount Koya, the Master still resides.