There are many obstacles to overcome when we use network services during a large-scale disaster, such as poor communication with unstable networks. Under such network environment, computers need to save network resources and to balance loads among nodes without user's operation. We propose the P2P Safety Confirmation System in which each node sufficiently achieves autonomous dynamic load balancing. This system is based on our proposed structured P2P network called Well-distribution Algorithm for an Overly Network (Waon), which does not require any network restriction and not incur additional maintenance costs during its load balancing. We implemented the system and evaluated node's behavior while nodes autonomously balance loads. Moreover we applied this framework to build a communication support system in natural disaster.