Meeting to unify Japan Socialist Party. From "Me de Miru Gikaiseiji Hyakunenshi"

Meeting to inaugurate Liberal Democratic Party. From "Showa Nimannichi no Zenkiroku vol.10"

In the general election held in February 1955 (Showa 30), the HATOYAMA Cabinet's ruling Japan Democratic Party failed to secure a majority. Meanwhile, moves to unify the Japan Socialist Party gathered impetus. The party had been divided into rightist and leftist factions due to differences over issues related to the San Francisco Peace Treaty. Under these circumstances, conservative forces stepped up efforts to join forces while the Japan Socialist Party was integrated in October 1955 (Showa 30). Capping Japan's political realignment moves in 1955 (Showa 30) was the formation of the Liberal Democratic Party following a merger in November between the Japan Democratic Party and the Liberal Party. The so-called 1955 system, in which two major parties confronted each other, was established in that year.

In 1960 (Showa 35), when the Cabinet was led by Prime Minister KISHI Nobusuke, the ruling and opposition parties were sharply divided over the proposed revision to the Japan-U.S. Security Treaty, throwing parliamentary proceedings into confusion. Outside the Diet, strong opposition was being mounted by activists against the proposal, an unprecedented movement in Japan's history. On 19 June, the bill for the revised treaty was automatically enacted. The following month, the KISHI Cabinet resigned en masse, followed by the inauguration of the Cabinet of Prime Minister IKEDA Hayato. Prime Minister IKEDA proposed "tolerance and perseverance" as his government's policy and adopted an economy-oriented policy aimed at promoting significant growth.