Every city that joins OASC becomes part of its Council of Cities (CoC) and is welcome to attend all CoC meetings. To be an OASC member, a city must belong to a national chapter, which requires at least two cities from the same country to apply. Each national chapter has a designated “National chapter coordinator,” who is the only one with voting rights on matters like MIMs and representation.

The National chapter coordinator serves as the key link between the OASC member cities in their country and the OASC Secretariat, facilitating communication and representing the collective interests of the cities.

For Japan, the national chapter coordinator is Takehiko Nagumo.