The author did in situ research for an MA in Asian Religions on Japan’s greatest saint, Kūkai, in his birthplace of Zentsūji, along the Pilgrimage of Shikoku that symbolically recapitulates his career, and at Kōya-san, the mountaintop monastery south of Kyōto that Kūkai founded in the early 9th Century. Kūkai was a key figure igniting the golden age of the Heian Period, but little was known outside of his home region about his origins and supportive social network before this investigation. The author relied on classical and contemporary historical sources in Japanese, including interviews with Buddhist priests.