Convention by citizens of Tokyo celebrating promulgation of the constitution 3 November 1946 (Showa 21) From "Yoshida Naikaku"

On 25 October 1945 (Showa 20), the Government set up the Constitution Investigation Committee on the constitution, chaired by MATSUMOTO Joji (the MATSUMOTO Committee). Its original purpose was only to investigate and study constitutions, but because of "domestic and foreign conditions" the purpose was upgraded to undertake the revision of the Meiji Constitution. The committee carried out its work secretly, and came up with two draft proposals, the more liberal of which was "scooped" by the Mainichi Shinbun several months later, on 1 February 1946 (Showa 21). Other newspapers unfavorably reviewed that draft proposal, as did GHQ, so GHQ took it upon itself to embark on constitution revision.

On 8 February 1946 (Showa 21), the MATSUMOTO Committee submitted its "Outline of Constitution Revision" but that was rejected by GHQ and replaced by General Douglas MACARTHUR's draft proposal, which was presented by the Government Section (GS) on 13 February. That proposal based upon the so-called MACARTHUR Three Principles enunciated on 3 February: (a) the preservation of the Emperor System, (b) the total renunciation of war, and (c) the abolition of the feudal system.

Upon receipt of the MACARTHUR draft from GHQ, the Japanese Government decided to base constitution revision on it. On 27 February Vice Bureau Chief IRIE Toshio and Bureau Chief SATO Tatsuo of the First Department of the Cabinet Bureau of Legislation began work on the Japanese Government draft. The draft was completed on 2 March and finishing touches in place by 5 March after allnight deliberations with GHQ. The "Outline of the Draft for a Revised Constitution" was announced the following day. After that, language was changed to the colloquiral style, and the final version was ultimately announced on 17 April 1946 (Showa 21) as the "Draft for the Revised Constitution".