Why were samurai (warrior) governments established in Japan? This is the question that I have been exploring in my research. Through this research, I seek to reveal certain historical characteristics of Japan, the only East Asian country in which samurai governments were formed. From the perspective of historical science, I have been elucidating the question by studying the cloister government, the Taira clan government, the Genpei War (a conflict between the Taira and Minamoto clans), the establishment of the Kamakura shogunate, and the literary Tale of Heike.