Myo-o is the Japanese term for Sanskrit “Vidyaraja,” a group of warlike and wrathful deities known in English as the Mantra Kings, the Wisdom Kings, or the Knowledge Kings. Myo-o statues appear ferocious and menacing, with threatening postures and faces designed to subdue evil and frighten unbelievers into accepting Buddhist law. They represent the wisdom of Buddhism, protect the Buddhist teachings, remove all obstacles to enlightenment, and force evil to surrender.
The most famous, Fudo Myoo is known as the great, fearsome king of wisdom, a protector of the Buddhist teaching. He is always shown with a furious, glaring face, in order to startle people into accepting the teachings of the Buddha. He carries a sword in his right hand which represents wisdom cutting through ignorance and a lasso in the other, in order to overcome and fight against the stubborn, sentient human nature, and “capture” them to show the truth of the Buddhist law.
He is in service to the Dainichi Nyorai Buddha, commanding that people awaken to the spirit of the Buddhist law, and looking to vanquish evil wherever he finds it. His countenance is intentionally fierce to fight against evil, and serves to startle people into accepting the great wisdom of Buddhism, the path to enlightenment.
The halo of flames encompassing Fudo Myoo represents the purification of the mind, by burning away the desire for all material things.
At the temple I stayed in Koyasan there was a morning ceremony called the Goma Shiki that consisted of burning wooden tablets where wishes have been written and consecrate them to Fudô Myo-o. We wrote a wish and who we were on a piece of wood,, that was then burnt in honour of Fudo-Myo-o, who can be seen overlooking the ceremoy.
