Kobo Daishi Kukai (774-835) is the founder. Kukai traveled to Chang’an in the Tang Dynasty, received esoteric Buddhism from Eka Ajari at Seiryu-ji Temple, and after receiving many secret teachings, returned to Japan and founded the Shingon sect.
He was given an important position by Emperor Saga, and was given the Toji Temple in Kyoto, and Koyasan, and founded Kongobu-ji Temple.
The head temple is Koyasan Kongobu-ji Temple. The principal image is Dainichi Nyorai, the body of the universe and the absolute truth.
It teaches that if you practice the true words of Dainichi Nyorai with your body, mouth, and mind (three secret practices), you will attain Buddhahood in your own body.
Until he entered Koyasan in 835, Kukai carried out his missionary work, welfare activities, and civil engineering projects such as irrigation ponds and bridges.
It is said that there are more than 5,000 Kobo Daishi legends nationwide, far exceeding the footprints of Kukai in history.
The legend of Kobo water, which says that when Kobo Daishi used his cane, the spring became a pond or a well, can be found all over the country. In the Edo period, people became familiar with Daishi as Daishi through the legend of Daishi and proverbs related to Daishi such as “Kobo is also a mistake in brush” and “Don’t choose Kobo brush”, and Daishi faith was born.
Koyasan became the center of Daishi faith as the place where Kukai entered.