The Japanese contribution to the First World War led to a reorganization of the West-Pacific-East-Asian region, thus creating the hotbed for the subsequent agitations of the European colonial policy in the Pacific as well as in the South and East Asian region. For better understanding of the further statements, one must elaborate on the Japanese foreign political interests before the First World War, and its home political conditions, respectively. In the beginning of the 20th century, the Japanese Empire was one of the climbers. Exuberant nationalism, together with the almost unlimited power of the military in the secret national council and in the military senate had the country become a totalitarian and imperialistically governed country, whose greatest challenge appeared to be the unrestrained expansion of its territorial dominion. Although Japan was – together with the USA – one of the real winners of the First World War, it was unable to make this victory a lasting success. After the unsuccessful participation in the Siberian intervention at the latest, Japan ought to have had change its views, but it unimpressedly continued its unrestrained and aggressive expansionism on the East Asian continent instead. With the crossing of the “Marco Polo Bridge” in 1937, this policy finally led to decline and, after more than eight years of privation caused by the total war on the Asian continent and in the Pacific, forced the end of militarism. In November 1918 all weaponry remained silent, and the victorious powers could start rearranging the world. Suitable palaces in Paris and its suburbs were destined for peace conference locations. The territorial regulations of the Peace Treaty of Versailles were important for Japan, for Kiautschou, which had been leased by China, was then returned to Japan. Kiautschou was governed by Japan until 1922, before it was returned to China on pushing by the USA. Moreover, the League of Nations induced the islands of the Northern Marians, the Marshall Islands and the Carolinas to be posed under Japanese South Sea Mandate – a so-called “C-Mandate” – which allowed the island regions to be governed according to Japanese law. It was, however, not allowed to put up military installations. The peace negotiations were also used by a delegation consisting of foreign Koreans and the temporary government of Korea in Shanghai to promote Korea’s independence, but the official authorities did not agree, as Korea was considered a Japanese colony. Japanese took also part in the realization of the resolutions of the peace conferences. This was the reason why Japanese Officers as delegation members attended the border-line regulation committees, thus co-determining the future new borders. Thus, General Staff Colonel Yamaguchi Juhachi attended the regulation committee which had to determine the border line between Hungary and Austria.