Taishan Fujun first appears in the Soushen Ji 搜神記, a Jin dynasty 晉朝 (265–420) compilation of tales attributed to Gan Bao 干寶 (d. 336). Continuing appearances in later tales re-popularized the deity during the Tang dynasty 唐朝 (618–907), during which time he became conflated with the deity Citragupta (described below). Prior to this conflation, he has no known iconography.

The worship of Taishan Fujun was transmitted to Japan where he was known as Taizan Fukun. He gained prominence within the divination tradition of Onmyōdō 陰陽道. In order to gain various worldly benefits such as an extended lifespan, aristocrats and rulers alike petitioned Onmyōji to perform the Rite of Taizan Fukun 泰山府君祭. This ritual was particularly popular during the Heian 平安 (794–1185) and Kamakura 鎌倉 (1185–1333) periods. As he was a non-Buddhist deity, Taizan Fukun was identified as a manifestation of Kṣitigarbha 地藏 according to honji suijaku 本地垂跡 theory. The worship of Taizan Fukun ceased in Japan when Onmyōdō and its offshoots, such as Tsuchimikado Shintō 土御門神道, were abolished by the Meiji 明治 government. He is not known to be worshiped today.

Citragupta began to appear within Buddhist texts during the early sixth century with the expansion of the Mahāmāyūrī-vidyārājñī-sūtra (佛說)大孔雀呪王經 into three fascicles. There, Citragupta appears among a number of non-Buddhist divinities that have been recast as protector yakṣas 夜叉 within the text. Citragupta appears next within a variety of scriptures relating to the mahākaruṇā-garbhôdbhava-maṇḍala 胎藏界曼荼羅, such as the garbhôdbhava ritual manuals (T 850, T 851) translated by Śubhakarasiṃha 善無畏 (637–735), the Taizang Tuxiang 胎藏圖像 iconographic manuscript (TZ. 57, 58), Yixingʼs 一行 (683–727) Dapiluzhe'na chengfo jingshu 大日經疏 (T 1796), and in all modern 'Genzu'  原圖 versions of the garbhôdbhava-maṇḍala. Despite this prominence, Citragupta is conspicuously absent from the text upon which the garbhôdbhava-maṇḍala is primarily based: the Mahāvairocanâbhisaṃbodhi-vikurvitādhiṣṭhāna-sūtra 大日經. Because the Mahāvairocanâbhisaṃbodhi is the only above-listed text to be transmitted to Tibet, Citragupta is unknown in Tibetan literature; he does not even appear in Tibetan iterations of the garbhôdbhava-maṇḍala.

An early description of Citragupta surviving in the Viṣṇudharmôttara-purāṇa was utilized as his standard iconography within the garbhôdbhava literature. He is pictured sitting, with a pen or brush in his right hand and paper in his left hand. Indian sources generally describe his clothing as 'northern-style' (Skt. udīcyaveśa), while Sino-Japanese sources generally depict him in the robes of a Tang magistrate. The Taizang Tuxiang provides Citragupta with a daṇḍa 檀拏 staff, surmounted with a skull. Although no Indian images of Citragupta with the daṇḍa staff are known, the staff became the godʼs standard attribute in all known Sino-Japanese images.

During the Tang dynasty, Citraguptaʼs role as a netherworld scribe became conflated with Taishan Fujunʼs role as a netherworld magistrate. By the ninth century, the name 'Taishan Fujun' began to refer to Citragupta (as appearing within the garbhôdbhava literature), the Chinese Taishan Fujun, or even a syncretic deity that combined aspects of both gods.

Although known more commonly as Taishan Fujun in China, Citragupta was transmitted to Japanese Shingon 眞言宗 Buddhism with the garbhôdbhava-maṇḍala and its related texts. Similarly to his non-Buddhist counterpart (see above), Citragupta was known in Japan as Taizan Fukun. While he continued to appear in Japanese ritual compendia, his role remained largely unaltered from Indian Buddhist sources. Continuing his role as the scribe of Yama, however, he appears prominently in every known variant of the enma ten mandara 閻魔天曼荼羅. His association with Yama and his retinue is further illustrated by his function as Taishan Wang 泰山王 (Jp. Taisan Ō), the seventh of the Ten Kings of Hell 十王.

During the late Heian and early Kamakura periods, Citragupta became associated with several deities, most notably Sekizan Myōjin 赤山明神, a guardian of Enryakuji 延曆寺, and Jinja Dashen 深沙大神, a deity that is said to have appeared to the monk Xuanzang 玄奘 (602–664) along his long journey to India. Bernard Faure has also noted his relationships to still other gods, such as Myōken 妙見, Matarajin 摩多羅神, and even Amaterasu 天照.

Also written as 太山府君, 大山府君, 泰山王, and 太山王. Citragupta is transliterated as 質多羅笈多. Also translated as 奉教官.

References:

Chatterjee, Asim Kumar. 1974. “Worship of Citragupta in Ancient India.”  In Ancient Indian Literary and Cultural Tradition. Calcutta:  Punthi Pustak. 134–140.

Elacqua, Joseph P. 2016. “Citragupta: A Case Study in Esoteric Buddhist Appropriation.” The e-Journal of East and Central Asian Religions 2 

Faure, Bernard. 2016. Gods of Medieval Japan. Honolulu:  University of Hawai'i Press.

Saitō Hideki  斎藤英喜. 2012. Onmyōdō no Kamigami陰陽道の神々 Zōho-ban 増補版 . Kyōto:  Bukkyō Daigaku Shōgai Gakushū Kikō.