In Japan, doctrinal studies within the Jōdo Sect and Jōdo Shinshū sects have played central roles in doctrinal studies of Pure Land thought. They have traditionally taken the teaching of Shandao (善導) as the absolute guiding principle, even regarding it as the global standard in Pure Land studies. However, in view of the historical fact that Shandao’s teaching was soon forgotten in China, and that it hardly left any trace of major influence in Korea, Japanese Pure Land studies centered on Shandao’s doctrine need fundamental revision. This paper examines the background to the idiosyncrasies found in Pure Land studies in Japan by analyzing the categorization of Japanese temples brought about by the One-Temple-One-Sect System (一寺一宗体制), which effectively limited doctrinal studies within each temple to that of its own sect.