A Rinzai Zen monk of the Muromachi period, said to have been the illegitimate son of Emperor Go-Komatsu. He entered Ankokuji temple in Kyoto at age six and took monastic vows. After rigorous training under the Sakai monk Kenzō Sōi, he studied under Kasō Sōdon at Daitokuji, receiving certification of enlightenment—which he promptly burned in a characteristically unorthodox gesture. He despised formalism and authority, plunging into the world of commoners and living freely with wine, meat, and women. His Chinese verse collected in Kyōunshū and other works are highly esteemed today. He fled the destruction of the Ōnin War (1467), moving from place to place, and became abbot of Daitokuji at 77. In his later years he was known for a deep love relationship with a blind woman named Mori. He died at 88. Famous also for his wit and wordplay, he is beloved by Japanese children as "Ikkyū-san."

A free spirit who thoroughly rejected formalism, authority, and hypocrisy. He sought the essence of Zen outside convention, choosing to live on the same level as ordinary people. Armed with humor and sharp critical wit, he satirized the corrupt Buddhist establishment and powerful figures throughout his life.

He left behind Kyōunshū, a masterpiece of medieval Zen literature. He contributed to the cultural revival of Daitokuji, and his influence extended broadly to renga poetry, tea ceremony, and Noh theater in Muromachi culture. The witty legends of "Ikkyū-san" continue to be told and beloved to this day.