With a view to launching the Covenant of Mayors in Japan, two preparatory meetings were held in March 2018. Experts were invited from the cities which were already signatories of what was the Compact of Mayors or Japanese Covenant of Mayors, as well as from ICLEI Japan, an important local government network in Japan. From the five cities which had already signed the Compact of Mayors, Tokyo Metropolitan Government, Yokohama City and Kitakyushu City sent experts, while Toyota City represented the six municipalities that have signed the Japanese Covenant of Mayors, which was launched in the country through an initiative of Nagoya University in 2015. Kyoto City also sent experts to the meetings as it is interested in becoming a new member of the Global Covenant of Mayors (GCoM).

Based on the discussion among and consultation with these stakeholders, it was decided to launch the Covenant of Mayors Japan with the founding members of 11 cities: 5 signatories of the Compact of Mayors and 6 signatories of the Japanese Covenant of Mayors. The commitment text and implementation schemes including the procedures for commitment, data and reporting as well as the temperate of SECAP (sustainable energy and climate action plans) were agreed upon by the founding members. It was also agreed that CoM Japan can be considered to be in a provisional phase until the number of signatories reaches a certain number. For example, if more than twenty cities have newly signed, it will move into full implementation phase.
CoM Japan has a Steering Committee which decides on important issues related to management and implementation. During the Provisional Phase, the Steering Committee will consist of members who are officials of local governments selected among the founding members of 11 cities and experts from two city networks: ICLEI Japan and COLGEI (Coalition of Local Government Environmental Initiatives). The committee can also nominate observers who can attend Steering Committee meetings. The Ministry of Environment will also send a person to each Steering Committee meeting. When CoM Japan enters the Implementation Phase, the Steering Committee will be restructured to be composed of mayors selected from the signatory cities.