Shukō, however, did not embrace the idea of a fully "wabi" approach to "chanoyu". By contrast, Takeno Jōō (1502–1555), who studied under one of Shukō's disciples, was totally dedicated to the elaboration of the "wabi" style in both tea utensils and the decor of the tea room itself. Jōō's contribution marks the transition between Murata Shukō and the fully developed Japanese tea ceremony of Sen no Rikyū (1522–1591). The historical figure considered most influential in the development of the Japanese tea ceremony was Sen no Rikyū. Rikyū served as tea master to both Oda Nobunaga (1534–1582) and Toyotomi Hideyoshi (1537–1598). 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 Toyotomi 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 has now dominates Japanese tea culture. In addition to the rustic tea room, Sen no 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 Sen no Rikyū to commit seppuku in 1591, Rikyū's descendants were allowed to continue in their profession.