National Treasures & Important Cultural Properties
of National Institutes for Cultural Heritage, Japan

The Shingon patriarch Kūkai (posthumous title Kōbō Daishi; 774–835) wrote this esoteric Buddhist text summarizing and explaining the Chinese monk Yijing’s (635–713) translation of the Diamond Sutra.

Six Chinese translations were made of the Diamond Sutra. The one by Kumārajīva (344–413) is the most frequently used, however, Kūkai used a later translation created by Yijing during the Tang dynasty (618–907). The Diamond Sutra attracted many followers in China, and miraculous tales of its efficacy in bringing benefits to believers were compiled in the Miracles of the Diamond Sutra (Ch. Jingang bore jing jiyan ji). The sutra also had a strong following in Japan. By the end of the Nara period (710–794), a large number of copies had been produced at state-sponsored scriptoriums, and belief in the powers and efficacy of this sutra grew even stronger during the Heian period (794–1185). Tales from the Chinese text Miracles of the Diamond Sutra were included in Japanese compilations of Buddhist tales such as the Record of Miraculous Events in Japan (J. Nihon ryōiki) and Tales of Times Now Past (J. Konjaku monogatari) .

The Sanbō-in of Daigoji Temple in Kyoto is believed to have originally owned this work. At some point, however, it was removed from the temple and cut into sections. The extant sections of the manuscript total some 150 lines.

This 38-line segment was passed down by the House of Takamatsu, a branch of the imperial line. Another known fragments is a 63-line segment in the collection of the Kyoto National Museum. An 86-line segment that was part of the preceding section of the original manuscript was destroyed in a fire during the Great Kantō Earthquake of 1923.

The backstory of this work is related to Fujiwara no Kadonomaro’s (755–818) votive act of producing 187 copies of the Diamond Sutra in the 10th month of Kōnin 4 (813). Some years earlier, in Enryaku 23 (804), Kadonomaro had traveled to the continent as an ambassador to Tang China on the same boat as Kūkai. Their ship met with a violent storm, and they drifted at sea for more than a month. At that time, Kadonomaro made a vow to the deities of 187 places that he would dedicate a copy of the Diamond Sutra to each one if the ship were spared. They eventually reached port safely, and Kadonomaro honored his promise when he got home by dedicating copies of the Diamond Sutra to the deities.

Kūkai wrote the dedicatory prayer for Kadonomaro’s sutras, and it is thought that Kūkai’s Explication of the Diamond Sutra was authored at the same time. This manuscript was likely a draft, as additions and corrections can be found throughout.