Shingon Buddhism was founded by a monk named Kuukai, who is more commonly referred to by his posthumous name of Koubou-daishi (“Great Teacher of Buddhist Doctrine”). In the year 804 he traveled to China and began a study of Esoteric or Tantric (Vajrayana) Buddhism which was then popular in that country.

Esoteric Buddhism includes central doctrines which cannot be written down and must be passed directly from teacher to student. Its rituals rely heavily on mantras (sacred sounds), mudras (sacred gestures) and mandalas (sacred images.)

Kuukai so impressed his teachers that by 806 they encouraged him to return to Japan to propagate Esoteric Buddhism there. Shortly thereafter the Chinese government began a campaign of persecution of foreign religions. Esoteric Buddhism was largely wiped out in China. Today, aside from Japan, it is mostly confined to Tibet.

Returning to Japan he gained fame not only as a great religious teacher but also as a talented civil engineer and a brilliant calligrapher. He built numerous temples, including a large complex of temples and monasteries on Mt. Koya (Kouya-san). He also set up a school that was open to all social classes.

Koubou-daishi is revered even by Buddhists of rival sects, and his life is surrounded by numerous legends. He is widely credited with inventing the Hiragana syllabary which made it possible to accurately represent the Japanese language using Chinese characters, though there is little solid evidence for this.

According to one story, before embarking from China he threw a vajra across the Sea of Japan, vowing to establish his headquarters wherever it landed. With the help of the local kami he eventually found it nestled in the branches of a pine tree on Mt. Koya. Visitors are still shown the pine tree near the Konpondaito Pagoda on Mt. Koya.

Shingon was never the largest sect in Japan and today it is relatively small with only about 2 million members, though it controls some of the country’s most historic and beautiful temples.