Hikokichi Ijoin was born in 1864. He was the eldest son of Yoshitsugu Ijuin, a former retainer of the Satsuma (Kagoshima) Clan.
Graduated from Tokyo University (1890) and became a diplomatic probationer.
Hikokichi Ijoin was a consul in Britain and Italy and ambassador in China and Italy. Became a baron (1920). He was a member of the Japanese delegation at the Paris peace conference following World War I. Was appointed Governor of Kwantung Leased Territory in Manchuria (1922) and Foreign Minister