This article describes the history of civic engagement at Nishigawa Canal Park in Okayama city, Japan. Nishigawa Canal Park was constructed in downtown Okayama from 1974 to 1982, and its total length is 2.4 km. Since 2008, citizens have held events in the park totaling over 70 days per year, with the support of the city’s Nishigawa Performers Project. By analyzing their machizukuri—community development through collaborative actions—we demonstrate the importance of public space in urban development from two points of view: participatory democracy and an eco-livable city. Okayama has rich experiences that show its citizens value a sustainable society. It also faces challenges in urban development carried out through collaboration between public policy makers, political leaders, and citizens.