Kawaji Toshiakira was born on April 25, 1801 in Bungo-no-kuni (now Oita Prefecture). From 1818 he held successive important posts in the Shogtmate Government at Edo. In 1852 he was appointed Chief Treasurer and at the same time was ordered to supervise the coastal defenses.
He built Daiba (forts) off the shore of Shinagawa as a defense against foreign warships, which visited Japan to force the government in to opening its ports to foreign shipping. He negotiated with a Russian mission as a representative of the Government and insisted that the area south of North Latitude 50 of Sakhalin and Itrurup of the Kuril Islands be annexed to Japan. In 1863 he filled the post of the Magistrate of Foreign Affairs, but soon became ill and retired.
He committed suicide on March 15, 1868 when the shogunate Government at Edo collapsed.