During his nine-month stay in China, the Japanese monk Saicho (767-822) was alleged to have been initiated into an illustrious esoteric lineage starting from a prestigious Indian Esoteric patriarch. It is also believed that Saicho's Chinese mentor, based on three esoteric texts translated by the Indian Patriarch, transmitted to him some particular forms of esoteric teachings, the core of which is preserved in one of the two dharma-transmission documents...