Shakyo (copying of a sutra) (写経)
Shakyo is a Buddhist practice to copy Buddhist scriptures, and it also means Buddhist scriptures that have been copied.
Shakyo was necessary to spread Buddhism in a time when printing technology had not been developed, and it was also necessary for many priests in a single temple to conduct ascetic practice, to give lectures, and to conduct research. Then, it started to be reasoned that the practice of shakyo would bring blessings.
In China, shakyo was stylized in the Rikucho period, and the practice of shakyo started to be popularized in the time of the Sui and Tang Dynasties. In Japan, complete Buddhist scriptures were copied in the Kawara-dera Temple in 673 for the first time, and a public shakyo center was established in the Nara period. A public shakyo center was also established in the Todai-ji Temple, and shakyo was practiced by those who practiced shakyo as a profession under a national project. In the Heian period and afterward, shakyo started to be practiced out of religious beliefs to fulfill personal prayers, not to spread Buddhism. When pessimism spread due to decadent-age theory, kyozuka (a mound of Buddhist scriptures) started to be built to put copied Buddhist scriptures in kyozutsu (a tube in which rolled Buddhist scriptures were kept) for burial.
There were also instances where people copied Buddhist scriptures on sukigaeshi gami (paper made from dissolved old paper) and as shihai monjo (an old document which was written on the other side of a piece of used paper) made of remaining letters that had been written by deceased family members and friends in order to hold a religious service for them. As an example of the former case, it is recorded in "Nihon Sandal Jitsuroku" (a history book written in the Heian period) that FUJIWARA no Tamiko, one of the wives of Emperor Seiwa copied the Lotus Sutra on paper made of melted letters that had been written by the Emperor when he was alive. As an example of the latter case, it is known that Fushimi tenno shinkan hokkekyo (the Lotus Sutra written by Emperor Fushimi himself) stored in the Myoren-ji Temple (Kyoto City) was written on the other side of a letter written by his father, Emperor Gofukakusa.
Whereas copied Buddhist scriptures are called shakyo, Buddhist scriptures that are created as woodblock prints are called kankyo and kankyo became popular in the Northern Sung Dynasty and afterwards.
For today's Japanese temples, shakyo generally means the practice of copying the Heart Sutra.