Shingon-shu Buzan-ha
buzan.or.jp
Shingon-shu Buzan-ha is based on the teachings of three great Buddhist masters: Kobo Daishi, who systematized the esoteric teaching of Shingon Sect, Kogyo Daishi, who restored his teachings in the 12th century, and Senyo Sojo (Archbishop Senyo), who founded the Buzan Division in the 16th century.
Shingon Buddhism
compsoc.net
Japanese history - Shingon, a major Japanese school of esoteric Buddhism.
Japanese Esoteric Buddhist Studies
asunam.com
With Asunam Sensei. The Shingon School, Kobo Daishi, Koyosan, and Three Secrets.
Shingon Buddhism Introduction
koyasan.org
One page intro.
Shingon Buddhist International Institute
shingon.org
The institute was set up to promote the understanding Japanese Shingon Buddhism. The pages here include Shingon Buddhist history and deities, rituals and teachings.
Koyasan and Shingon Esoteric Buddhism
mandala.ne.jp
A short biography of Kobo Daishi.