Sanpokojin (or also called sanbokojin) is one of the Buddhist beliefs peculiar to Japan. It is believed that sanpokojin protected three treasures of Buddhism--Buddha, the sutras and priesthood--and abhorred uncleanliness.
Kojin (the god of cooking stoves) refers to a guardian deity of Buddhism and Buddhist temples. Japan had two concepts of Aramitama and Nigitama. There was originally no custom of enshrining the former because it was an evil deity having harmful influences, but along with the introduction of Buddhism, a custom of setting an evil deity as a guardian deity by enshrining evil deities such as yaksha (Buddhist guardian deities sometimes depicted as demonic warriors) and rakshasa (a type of evil spirit) in India was introduced. Therefore, ancient Aramitama, which was enshrined, was set as Kojin. This means that the Hindu custom of setting evil deities as guardians and Goho zenjin (good deities protecting dharma) after such evil deities became believers of Buddhism was also conducted in the same manner in the Japanese environment.
Kojin as the statue form was not a venerable image Buddhist statue originating from India but was instead a statue of noble character independently developed in the belief of Japanese Buddhism, and was represented by sanpokojin. It is considered that Kojin was formed as a result of blending the ancient Japanese Aramitama, adopting a form of Yashashin originating from ancient India, and various elements such as Shinto, Esoteric Buddhism, mountain worship and so on. Japan has approximately 300 shrines and temples that enshrine Kojin.
A general statue form of sanpokojin is a Buddhist statue with three faces and six arms or with eight faces and six arms (with five small faces on the Buddhist statue with three faces). Because of its nature of punishing terrible evils, sanpokojin expressed its anger with its hair erect and a fierce look in its eyes, and was similar to Myo-O Zo (Statue of Wisdom Kings) in Esoteric Buddhism.
Because it is considered to have been a deity removing uncleanliness and disasters, Sanpokojin has been believed as a god of fire and kamado (kitchen ranges) and has often had a place of honor as Kamadogami (the god of kitchen ranges). Because a kitchen and kamado have been believed to be the cleanest places in Japan, the common people came to believe in Kamadogami. Many Buddha statues were made in and since the recent times.
Aum Kampa Kampa Svaha
The above means 'Aum (sacred sound), Kenba, Kenba, Svaha (prayer for accomplishment)' in Japanese. Sanpokojin was considered to be the same as Kenbaya, which was a deity of earthquakes, kenzoku (disciples or followers of Buddha) of Nitten, as preached in Vol. 5 of Dainichikyo-sho under the syncretism of Shinto and Buddhism. The etymology of Kenbaya was "Kampa" (seismic wave) in Sanskrit.