For more than two centuries from the mid-sixteenth to the mid-eighteenth century, one particular item dominated the fashion of wabicha, a form of tea ceremony, in Japan: tea bowls obtained from Korea, commonly called Kōrai chawan (高麗茶碗), or Korean tea bowls. Korean tea bowls held the key to the evolving aesthetic of wabicha, which was highly refined by Sen no Rikyū (1522–1591) and inherited by other eminent tea masters in Tokugawa Japan. Despite their prominence in the world of wabicha, Korean tea bowls have not often been studied. This article traces the cultural trajectory of Korean tea bowls from the perspective of trade and piracy, border-crossing cultural flow, classification, and acculturation. It then explores the question of what made Korean tea bowls so popular in the world of Japanese wabicha by focusing on four factors: the culture of the upper-class samurai, tea, and Zen Buddhism; the exoticism of Korean tea bowls; commercialism and political power; and the household profession of tea masters. Korean tea bowls, which symbolized the beauty of wabicha, served as a catalyst for a move away from a Chinese-centered aesthetics of tea culture in medieval times and toward a Japan-centered aesthetics of tea culture from the mid-eighteenth century onward.