From Sanuki to Chang'an
Kūkai belonged to the Saeki clan of Sanuki and was known in childhood as Mao. Classical study preceded Buddhist practice. His Rōko shiiki of 797, later revised as Sangō shiiki, explained a religious choice through comparison of Confucian, Daoist and Buddhist teachings.
He travelled to Tang China in 804, studying language and esoteric Buddhism in Chang'an under Huiguo at Qinglong Temple. Returning in 806, he brought texts, mandalas and ritual implements and submitted a catalogue to the court, documenting material as well as doctrinal transmission.
Mount Kōya and Tō-ji
Permission to establish a religious centre on Mount Kōya came in 816. In 823 Emperor Saga entrusted him with Tō-ji in Kyoto. Mountain training and a capital institution connected different aspects of practice, clerical education and court ritual.
Kūkai advanced construction at Tō-ji and established the Shugei Shuchi-in school in Kyoto. His activities also included repairs at Mannō Pond in 821. Teaching, building, ritual and public works all formed part of his career after returning from China.
Writings and handwriting
Works including Ben kenmitsu nikyō ron and Jūjūshin ron developed his religious arguments. Shōryōshū preserves prose, poems, memorials and letters, while Bunkyō hifuron concerns literary theory.
The surviving Fūshinjō letters to Saichō and Kanjō rekimei list of initiation recipients also preserve handwriting and personal networks. Kūkai died at Mount Kōya in 835 and became an enduring object of devotion; later sacred narratives form a further layer of that reception.