Gozu Tenno (also known as Mutō-no-Kami) is a uniquely Japanese deity whose existence is unconfirmed in foreign lands like India, China, or Korea^[1]. Several theories regarding his origin coexist and remain academically unconfirmed: 1) A Buddhist origin theory claiming he is the guardian deity of Jetavana (an ancient Indian monastery where Shakyamuni preached). The name 'Gozu' (ox head) is said to derive from Mount Gośīrṣa in Magadha, India, known for sandalwood, where a guardian named 'Gozu Tenno' was purportedly worshipped. 2) A Korean Peninsula origin theory attributing him to Mount Sudusan, introduced to Japan by ancient Korean immigrants (related to Mount Gozu where Dangun descended in Korean founding myth). 3) A syncretic theory suggesting he is an ancient Japanese immigrant/agricultural deity (the ox being a symbol of farming) reinterpreted through Buddhism and Taoism. Though conclusive evidence is lacking, immigrant influence and his later syncretism with Susanoo-no-Mikoto are the prevailing views from the Middle Ages onward.

The core narrative of his worship is the Somin Shōrai legend found in the 'Bingo-no-kuni Fudoki' (compiled in the early 8th century, now surviving only as fragments cited in the 'Shaku Nihongi')^[3]. While traveling to the Southern Sea to marry the Dragon King's daughter, Mutō-no-Kami (= Gozu Tenno; 'Mutō' is also theorized to derive from the ancient Indian Maheśvara) sought lodging at the home of the brothers Kotan Shōrai and Somin Shōrai in Bingo Province (modern-day eastern Hiroshima). The wealthy elder brother, Kotan Shōrai, refused him, while the poor younger brother, Somin Shōrai, welcomed him with a humble meal of millet. Years later, Mutō-no-Kami returned with his eight divine children and told Somin Shōrai, 'Wear a woven reed ring (chinowa) around your waist and chant "I am a descendant of Somin Shōrai" to escape the plague,' before departing. The next day, Kotan Shōrai's entire family was wiped out by the plague, while Somin Shōrai's family survived thanks to the chinowa. This is the origin of the 'Amulet of Somin Shōrai's Descendants' (an amulet placed at doorways) and the 'Chinowa-kuguri' (a purification ritual held at the end of June), rituals still performed at Gion shrines, Tenno shrines, and Ise Jingu nationwide.

Kyoto's Yasaka Shrine (formerly Gion Shrine / Kanjin-in Gion Shrine / Gion Kanjin-in) is the hub of Gozu Tenno worship^[4]. The shrine's history holds multiple theories: 1) Founded in 656 by the Korean envoy Irishi, who enshrined Susanoo from Mount Gozu (most plausible); 2) Enshrined by Ennyo, a monk from the southern capital, in 876; 3) The Imperial Court began praying at Gion during the great plague of 869 (the origin of the Gion Goryo-e). Ranked among the twenty-two elite shrines during the Heian period, the Gion Shrine became the most critical religious center for the Imperial Court, nobility, and Kyoto's citizens.

The Gion Festival was established in 869 as a ritual for Gozu Tenno (= Susanoo) to ward off plagues and is one of Japan's three major festivals (alongside the Aomori Nebuta and Awa Odori)^[5]. When a massive plague swept Kyoto and the nation in 869, the Imperial Court ordered prayers at the Gion Shrine. They created 66 halberds (hoko) representing the 66 provinces of the time to gather the plague gods, then banished them to Shinsen-en (modern-day Nakagyo-ku, Kyoto) — an event known as the 'Gion Goryo-e.' It evolved through the medieval and early modern periods, establishing the Yamahoko float procession, folding screen displays, and Yoiyama eves during the Muromachi period. It is now a month-long summer hallmark of Kyoto and was registered as a UNESCO Intangible Cultural Heritage in 2009, representing the pinnacle of Kyoto's tourism resources.

Among other major centers of Gozu Tenno worship, Hiromine Shrine (Hiromineyama, Himeji City, Hyogo Prefecture; supposedly founded by imperial decree of Emperor Shomu in 733, with alleged involvement by Kibi no Makibi) claims to be the 'Head Shrine of Gozu Tenno,' asserting that Kyoto's Gion Shrine was established as a branch of Hiromine^[7]. However, due to lengthy medieval and Edo-period disputes over hierarchy among Kyoto's Gion, Hiromine, Tsushima, and Yasaka, the academic consensus on the 'true head shrine' remains undetermined. Tsushima Shrine (Tsushima City, Aichi) serves as the core of Gozu Tenno worship in the Tokai region^[8], with its Tenno Festival (August) being one of Japan's three major river festivals. The countless shrines nationwide bearing the names 'Tenno', 'Yakumo', 'Gion', 'Susanoo', or 'Hikawa' demonstrate the vast spread of Gozu Tenno worship.

With the Shinto-Buddhism Separation Order of the Meiji Restoration (1868) and the abolition of Shugendo (1872), the Buddhist title 'Gozu Tenno' was banned, and all Gozu Tenno, Tenno, Gion, and Kanjin-in shrines were forcibly renamed as shrines dedicated to Susanoo-no-Mikoto^[6]. Kyoto's Gion Kanjin-in became 'Yasaka Shrine,' while local shrines were renamed to Yasaka, Susanoo, Hikawa, or Gion shrines. However, commoners retained colloquial names like 'Tenno-san' and 'Gion-san,' and folk customs such as passing through the chinowa, the Somin Shōrai amulets, and the Gion Festival persisted seamlessly. During the modern COVID-19 pandemic (2020-), the Gion Festival and chinowa rituals regained attention, reawakening memories of Gozu Tenno as the deity of plague dispellment. In folklore and religious history, he is positioned as 'the greatest victim of the Shinto-Buddhism separation.'