We studied the social system to maintain collaborative activities for restoring and conserving coastal pine forests in Karatsu City, Saga Prefecture, Kyushu, Japan. Governance has been structured and functioned in most conservation processes; administrative offices of the state, prefecture, and city, business sector, and Civil Society Organization have acted interdependently, and network members have continuous interaction under the management of an NPO group known as KANNE. KANNE has filled in a structural hole in the social network. KANNE plays a special role as the hub. Social ties, however, are very weak, and hence the system continuity is fragile. If KANNE stops its work, the network structure will collapse. As an internal circumstance of KANNE, most management works have been governed by the secretary-general, and any person who can act as a substitute is now absent. Installing a system to develop human resources within KANNE is important to retain conservation activities.