The Twenty-One Demands (Japanese: 対華21ヶ条要求, romanized: Taika Nijūikkajō Yōkyū; simplified Chinese: 二十一条/廿一条; traditional Chinese: 二十一條/廿一條; pinyin: Èrshíyī tiáo) was a set of demands made during the First World War by the Empire of Japan under Prime Minister Ōkuma Shigenobu to the government of the Republic of China on 18 January 1915. The secret demands would greatly extend Japanese control of China. Japan would keep the former German leased territory it had conquered at the start of World War I in 1914 and would be strong in Manchuria and South Mongolia while having an expanded role in railways. The most extreme demands (in section 5) would give Japan a decisive voice in finance, policing, and government affairs. The last part would make China in effect a protectorate of Japan, and thereby reduce Western influence.
Japan was in a strong position during the course of the war as the Allies were in a stalemate with their rivals, the Central Powers. The United Kingdom and Japan had a military alliance since 1902, and in 1914, the UK had asked Japan to enter the war. China published the secret demands, upsetting the Americans and British. They were sympathetic and forced Japan to drop section 5 in the final 1916 settlement. Japan gained little in China and lost a great deal of prestige and trust from both the United Kingdom and the United States.