Esoteric Japanese sect based on an interpretation of 9th-century Chinese Buddhism .
It holds that the Buddha 's secret wisdom can be developed through special ritual means (see Yoga ) employing body, speech, and mind, including the use of symbolic gestures, mystical syllables, and mental concentration. The whole is intended to arouse a realization of the spiritual presence of the Buddha inherent in all living things. Shingon's main scripture, the Mahavairocana Sutra ("Great Sun Sutra"), is not canonical in other Buddhist schools. Shingon is properly considered a form of Vajrayana , though it was much modified and systematized by Kūkai .