立憲民政党
Later in 1924, Kawasaki was recalled to Tokyo to assume the post of Director-General of the National Police Agency under the Home Ministry. He became Deputy Home Minister in 1925. In 1926, he was invited to take a seat in the House of Peers in the Diet of Japan. He was recruited by Osachi Hamaguchi and Wakatsuki Reijirō to join the "Kenseikai" political party, and in 1927 joined the "Rikken Minseitō".