Kūkai’s Secret Purpose For The Shikoku Pilgrimage

The Sacred Substance Kūkai Sought

The approximately 1,400-kilometer pilgrimage route known as the “Shikoku 88-temple pilgrimage” (Shikoku Pilgrimage, 四国八十八ヶ所), commonly referred to as the Henro (遍路), has long been traversed by countless Buddhist devotees. However, it is said that Kūkai (空海, 774–835), the founder of the Shingon school of Buddhism, traditionally credited with establishing this pilgrimage route, had a hidden purpose. Rather than solely opening the pilgrimage for religious devotion, Kūkai was also believed to have been tasked by imperial decree with conducting surveys and traversing the entirety of Shikoku. Consequently, there remain alternative theories about attributing the pilgrimage’s origins solely to Kūkai. Personally, I also feel that the pilgrimage was less a matter of faith and more likely traces of a survey mission that later became beautified from a religious perspective by subsequent generations.

Of course, this is also related to the fact that Kūkai himself was originally from Shikoku. Born in the coastal region of Sanuki Province (present-day Kagawa Prefecture) in 774, Kūkai went on to accomplish numerous extraordinary feats, eventually retreating to Mount Kōya in Wakayama, where he founded Shingon Buddhism (真言密教). A key question arises: Why was Mount Kōya chosen as the sacred site for Shingon Buddhism? A sage as intelligent as Kūkai surely had substantial reasons for selecting this location. With numerous legends surrounding him, the true nature of Kūkai remains elusive. Therefore, this article will examine him from a different angle—not merely from the perspective of esoteric Buddhist faith, but also considering the deep political intentions of the emperor and the imperial court at the time.

In a previous article, I wrote about how Kūkai, initially just an unknown monk, was suddenly selected to participate in the state-sponsored diplomatic mission to Tang China (遣唐使), significantly shortening his required 20-year study period as an overseas monk and returning after only two years. Moreover, within that brief period, Kūkai received full transmission from Huiguo (恵果阿闍梨), the most distinguished Chinese monk of his era. It is said that Huiguo personally chose Kūkai as his successor, urging him to “return to your homeland immediately and establish Esoteric Buddhism there.” This event may be difficult to fully appreciate today, but it was unprecedented compared to Saichō (最澄), another prominent Japanese monk aboard the same diplomatic voyage. (Saichō later became the founder of the Tendai school, establishing Enryaku-ji Temple on Mount Hiei.)

Notably, Kūkai eagerly collected and purchased numerous Buddhist texts unknown in Japan while in Tang China, bringing them back home and presenting them to the imperial court. According to some accounts, the vast number of scriptures Kūkai introduced did not overlap at all with existing Japanese texts, suggesting he may have read every Buddhist work available in Japan before his journey. Such a feat would be impossible for an obscure monk without privileged access to state-held documents.

Additionally, given Kūkai’s lack of personal funds, the fact he was able to purchase numerous scriptures and Buddhist statues suggests he received substantial financial backing, hinting at his involvement in some undisclosed, state-sponsored project. However, the full extent remains unknown, leaving room for many intriguing hypotheses. Thus, Kūkai, a mysterious superhuman figure, continues to fascinate many Japanese people today.

Considering the possibility that the pilgrimage route was established in 815 after Kūkai’s return from Tang China, it becomes clear that during his time abroad, he likely acquired diverse knowledge—not only of Esoteric Buddhism but also of Confucianism, Taoism, and other disciplines, integrating them comprehensively in pursuit of something specific.