From “The Giles Laws “

6. Kukai and Esoteric Buddhism

Kukai, also known as Kobo Daishi, (774-835) was a contemporary of Saicho, being born only seven years after him. He was born into the Saeki clan in the Sanuki province (present-day Kagawa Prefecture), and at the age of fifteen was sent to a national college in Nara where he was soon recognized as a genius. However, he soon became disenchanted with the idea of an official career and at the age of twenty left to travel around the country.

He did not take up Buddhism for worldly fame; rather, he wanted to share the experience that Shakyamuni had undergone in achieving enlightenment. Trying to emulate Shakyamuni in every way, Kukai renounced a secular life and began traveling around the mountains and fields of Shikoku. He adopted the practice of meditating under a waterfall in the southern part of Tokushima, then moved through the mountains to Tosa (present-day Kochi Prefecture). Later, at Mt. Otaki in Awa (present-day Tokushima Prefecture), he met a hermit who offered him some valuable advice:

You will not find your way through meditating under a waterfall; you need to go somewhere where you can see the sky and the sea. You should follow the coast southwards as far as Hiwasa village, then, taking a hatchet, you should cut a path through the woods. If you are not bitten by a poisonous snake en route, you should arrive at Murotozaki, where the demons are said to appear, within two days.

This hermit was a psychic who had the power to read minds. At this time Kukai was eager to master a supernatural power called Kokuzo-Gumonji-Ho (a method of enhancing the abilities to understand and memorize all the Buddhist scriptures) but, as the hermit said, this was not something that he could achieve through meditating under waterfalls. Kukai headed for the Murotozaki (Muroto Cape) as the hermit suggested, and when he arrived at the very tip of the cape, now called Hotsumisaki, he found a cave that would be ideal for his purposes. Shakyamuni had achieved enlightenment after meditating in the state of the Middle Way under the Bodhi tree for seven days, and Kukai aimed to emulate this.

Using my second sight I can see a cave; the entrance is two and a half meters (eight feet) in diameter and it is about twenty meters (sixty-five feet) in depth. It would appear to have been carved out of the cliffs by the waves of the Pacific. Kukai sat and meditated here for approximately twenty days, eating roasted rice he had carried with him and roots that he found in the surrounding mountains. The miracle occurred at dawn of the fifteenth day.