Buddhist chant was introduced to Japan together with Buddhist doctrines, first from Korea and later from China. Already in the eighth century the major Buddhist temples in Nara had their own music departments. One of the most famous examples of an early shōmyō performance is the eye opening ceremony of the Great Buddha of Tōdaiji 東大寺 in 752, where more than one thousand monks are supposed to have chanted the pieces Nyoraibai 如來唄, Sange 散華, Bonnon 梵音 and Shakujō 錫杖. Kūkai 空海 (774–835), the founder of the Japanese Shingon school 眞言宗, is supposed to have transmitted the pieces of the core repertoire of Shingon shōmyō from China. For Tendai shōmyō Saichōʼs 最澄 (767–822) disciple Ennin 圓仁 (794–864) was very important as he is said to have transmitted many important shōmyō pieces from China and thus laid the foundation of the shōmyō tradition of the school. In the ninth and tenth centuries, liturgical genres in Japanese were developed and thereby chants in the vernacular language were added to the shōmyō repertoire that had previously consisted of chants in Sanskrit and Chinese. Some of the new chants were composed in kanbun 漢文 (Chinese) but then recited in kundoku 訓讀 (i.e., hyōbyaku 表白, jinbun 神文, saimon 祭文, rongi 論議, kōshiki 講式), whereas others were composed in Japanese (i.e., wasan 和讚 and kyōke教化). In Buddhist ceremonies, instrumental music (bugaku hōe 舞樂法會) was also performed, including dance pieces, known today as gagaku 雅樂, was performed .

The shōmyō of the schools founded in the Kamakura period is mainly based on that of the Tendai school, since these schools were mainly founded by priests who had trained at Hieizan 比叡山. In the end of the seventh century, the Chinese monk Yinyuan Longqi 隱元隆琦 (1592–1673) introduced Buddhist music and ritual from Ming China to Japan. This was the last introduction of Buddhist music from China to Japan. Buddhist priests developed various systems for notating the melodies of shōmyō, called hakase 博士. The oldest extant examples date from the eleventh century. The oldest printed music notation in the world is a shōmyō notation entitled Shōmyōshū 聲明集 printed at Kōyasan 高野山 in 1472. Shōmyō pieces are categorized by their language in chants in Sanskrit (bonsan 梵讚), chants in Chinese (kansan 漢讚), and chants in Japanese (wasan 和讚). Another categorization is by the style of chanting: singing (utau shōmyō 歌う聲明), recitation (kataru shōmyō 語る聲明), and reading (yomu shōmyō 讀む聲明).

References:

Mross, Michaela. 2009. “A Survey of the Literature on shōmyō in Europe and America.”  In Bukkyō seigaku ni kiku kanjion: bonbai ni koin wo saguru 仏教声楽に聴く漢字音─梵唄に古韻を探る. Nishogakusha Daigaku. 206–214.

Nelson, Steven G. 2003. “Shōmyō: The Buddhist Chant of Japan.”  In Buddhist Ritual Chant from Korea and Japan. New York:  Japan Society. 12-23.

Sawada, Atsuko. 2002. “Buddhist Music in Japan.”  In Garland Encyclopedia of World Music: East Asia. New York and London:  Routledge. vol. 7 611–618.