Hunter Dukes at the Public Domain Review describes a Japanese rebus system; after describing the sad fate of Miminashi Hōichi (Hōichi the Earless), he writes:
If incantatory texts of Mahāyāna Buddhism work through recitation, are the illiterate barred from enlightenment, should they lack the supreme linguistic recall of Hōichi? The answer requires knowing more about literacy and language in Japan. The stakes of correct recitation were high in the pre- and early-modern era, with strict rules for pronunciation existing since the 1100s, and sutra recitation (dokyō) becoming an artform in the following century. Charlotte Eubanks tells the story of Emperor Goshirakawa, who supposedly incinerated a wing of the imperial palace after mispronouncing “a single character of the Lotus Sutra”.
This is to say, even for the literate, the Buddhist scriptures could be vast palimpsests of code-switches and calques. First of all, most East Asian canons of sacred Buddhist texts — known as Tripitaka and venerated by practitioners in Korea, Vietnam, and Japan — have long been written in Classical Chinese. As Greg Wilkinson notes, for those who can read this Tripitaka, the canon’s lack of punctuation, the tonal requirements of Chinese, and the presence of Sanskrit transliteration, makes it “very difficult to understand for a Japanese reader without special knowledge and training”, and almost as difficult to pronounce “correctly”, given the variation in dialects and vernacular speech across the archipelago.
In order to circumvent these issues in the seventeenth century, Japanese printers began creating a type of book for the illiterate, allowing them to recite sutras and other devotional prayers, without knowledge of any written language. The texts work by a rebus principle (known as hanjimono), where each drawn image, when named aloud, sounds out a Chinese syllable […]. Famously, the Japanese physician, scholar, and travel writer Tachibana Nankei (1753–1805) reproduced an early example of a Heart Sūtra for the illiterate in his 1795 Travelogue of East and West (Tōzai yūki). […]
As these texts were often most used in rural, agricultural regions, the chosen pictograms reflected the lived experience of their “readers”: the implements of work and rice farming (sieves, saws, paddies); domestic animals (from rats to monkeys); and imagery related to fertility, pregnancy, disease, and death. “Villagers, decoding these pictures and pronouncing them aloud in their local dialect”, writes Eubanks, “would thus produce sounds similar to those pronounced by educated clerics”. Furthermore, the presumed incantatory and magical power of an esoteric teaching, in a nearly incomprehensible language, coupled the sounds and promises of spirituality to the visual realm of everyday life.
Lots of striking images at the link.
The protective body-calligraphy turns up also in the superb film Ugetsu.
https://en.wikipedia.org/wiki/Ugetsu
I have Japanese relatives for whom sutra recitation is still an art form. Perhaps not serious enough for an error to provoke arson, but close.