Kukai (空海) is one of the intellectual giants in the history of Japan, best known for being the founder of Shingon esoteric Buddhism in Japan. In 804, he went to China and met Master Huiguo (恵果), from whom he received initiation into the lineage of Shingon (真言宗) esoteric Buddhism, and he succeeded his master to become the eighth patriarch.
During his stay in China, Kukai learned Sanskrit and studied Indian Buddhism, as well as the arts of Chinese calligraphy and poetry.
In 806, Kukai returned to Japan with a large number of Buddhist texts many of which were new to Japan. In 816 he began building a monastery on Mount Koya (高野山).
Kukai is also known for his accomplishments and innovations in social welfare, public education, lexicography, language, literature and poetry, literary theory, calligraphy, art, painting, wood-carving, sculpture, music, civil engineering, architecture, etc.
Kukai died in 835 at the age of 61. In 921, he posthumously received from Emperor Daigo (醍醐天皇) and his court, the honorific title, Kobo Daishi (“Great Teacher Who Spread the Dharma” 弘法大師).