Rikyū served as tea master to both daimyos Oda Nobunaga and Toyotomi Hideyoshi. He lived during the upheavals of the Sengoku period, in which political and social structures were radically transformed. Rikyū grew up in Sakai, where the wealthy merchant class was able to establish itself as a cultural and economic force capable of shaping Japanese tea culture. Rikyū, the son of a Sakai fish merchant, studied tea under Takeno Jōō. Like Jōō, he was a proponent of the wabi style of tea. At this time, the tea ceremony played a prominent role in politics and diplomacy. Nobunaga went as far as to prohibit anyone other than his closest allies from practicing it. The austere wabicha style Rikyū advocated was less favored for these political gatherings than the more lavish mainstream style. After Nobunaga's death, Sen no Rikyū entered the service of Hideyoshi and constructed a simple wabi tea hut called Taian, which became one of Hideyoshi's favorite tea rooms. In contrast to the shingled roof preferred by Shukō, Rikyū specified a thatched roof. Called the "North Pole of Japanese aesthetics", this room exemplifies the rustic wabi style that came to dominate Japanese tea culture. In addition to the rustic tea room, Rikyū established the etiquette of the modern tea ceremony as well as the ordained procedure and the choice of utensils to be used. He also developed the idea of the nijiriguchi, a small entryway through which guests must crawl to enter the tea room. Though Hideyoshi forced Rikyū to commit seppuku in 1591, Rikyū's descendants were allowed to continue in their profession. The three main schools of the traditional Japanese tea ceremony today, the Omotesenke, Urasenke, and Mushakōjisenke, were all founded by children of Sen no Sōtan, Rikyū's grandson. Teaware Developments in the Japanese tea ceremony during the Sengoku period motivated new trends in Japanese teaware. Rikyū's disciple Furuta Oribe served as Hideyoshi's tea master after Rikyū's death. Oribe's preference for green and black glazes and irregular shapes led to a new style of pottery called Oribe ware. Rikyū also influenced Japanese tastes in ceramics, rejecting the smooth regularity of Chinese-influenced tenmoku ware in favor of uneven rice bowls produced by ethnic Korean potters in Japan. This style of tea bowl or chawan was called raku ware after the name of the Korean potter who produced the first pieces for Rikyū's tea ceremonies, and is known for its