Gozu Tenno (牛頭天王)
Originally, Gozu Tenno (gośīrşa) was an Indian deity and the guardian deity of Gion-shoja (the Jetavana monastery). Later on, he amalgamated with the Japanese deity Susanoo. When the term "Tenno" alone is used, it usually means Gozu Tenno.
Although he has the horns of ox on his head and looks like Yasha (a class of semi-divine being usually considered to be of a benevolent and inoffensive disposition but sometimes also classified with malignant spirits), his figure resembles that of a human being.
As mentioned above, he is perceived as the guardian deity of Gion-shoja but he also is perceived as the suijaku (trace manifestation) of Yakushi-nyorai of Joruri-sekai (the realm known as Joruri or Pure Lapis Lazuli in the eastern quarter, Sk: Vaiduryanirbhasa). He is also said to be a deity stemming from Ox-head Mountain of Shiragi (the Silla dynasty). According to the extant "Bingonokuni Fudoki (ancient records of culture and geography of Bingo Province)" included in "Shaku Nihongi (Chronicle of Japanese History)," he was a prince of Buto Tenjin, his name was written as Gozu Tenno, he married a daughter of Shakara Ryuo, one of the Hachidai Ryuo (Eight Dragons) and he had eight princes.
In Japan, he amalgamated with Susanoo as he was a deity of ferocious nature and was enshrined at Yasaka-jinja Shrine in Gion, Kyoto and was worshiped as Joeki-shin (a god that protects against plague). He is said to be a deity who has concurrently the aspect of Yakubyo-gami (a deity of the transmission of epidemics). It is said that although he spreads diseases, he bestows remedies for all diseases on farmers who welcome him kindly. During the Heian period, people in urban areas started to worship him and he became the object of worship in Gion Goryo-e (the Gion Matsuri Festival). The faith for Gozu Tenno and Susanoo, which is the syncretism of Shinto and Buddhism, is called Gion veneration, which had spread nationwide by the Medieval period.
He was enshrined at Hiromine-jinja Shrine, Yasaka-jinja Shrine, Tsushima-jinja Shrine, Hikawa-jinja Shrine and their branch shrines, but subsequent to the separation of Buddhism and Shintoism in the Meiji period, these shrines have became shrines to Susanoo. However, in Nara, Kyoto and Niigata prefectures and others nationwide, there still are several shrines, including Tenno-jinja Shrine, that enshrine Gozu Tenno.
Many of the place names that include the word 'Tenno,' such as 'Tennoz Isle,' are derived from Gozu Tenno.
Sominshorai Shison-no-mon (the gate for the descendants of Sominshorai)
Once upon a time, Gozu Tenno went on a journey in the disguise of an old man and asked for lodging at a certain village. On this occasion Kotanshorai, the wealthy younger brother, treated Gozu Tenno coldly, but the elder brother, Sominshorai, despite being poor, welcomed and entertained Gozu Tenno kindly.
Then, Gozu Tenno disclosed his identity and declared, 'In the near future, mortal disease will run rampant in this village, but I will save your family members.'
As predicted by him, when mortal disease rampaged the village, all the family members of Kotanshorai died but those of Sominshorai survived.
Even today, Yasaka-jinja Shrine and other shrines distributes red paper cards with "Sominshorai shison-no-mon" written on them in gold-colored characters, and the origin of this practice is the historical event mentioned above.
The reason for having gold-colored characters on red paper is that, according to Onmyo-do (the way of yin and yang), it is believed that 'these colors are what Yakubyo-gami detests.'