This paper presents micro finance as a traditional system of mutual help networks in East Asia. These are called “Rotating Savings and Credit Associations” (ROSCAS) and can also be seen in other areas. Micro finance means that invested money is small and managed by members. Mutual help actions are divided into three categories: reciprocal, redistributional, and unidirectional action. The content of redistribution is labor, goods, and money. ROSCAS are the distributional action of money. It has been called tanaomoshi or mujin in Japan. ROSCAS have different names: South Korean ke, Chinese kai (huì), and Taiwanese hyokai (biāo huì) can be compared with the already well-studied Japanese case through the results of an interview survey and fact-finding fieldwork study. The purpose of the paper is to show that ROSCAS are important not only economically but also socially in terms of friendship and bonds. The economy is embedded in social relations and institutions. Although ROSCAS have almost disappeared from modern life and some are interest-oriented, they contributed to sustainable communities and can still be identified in East Asia. The paper concludes that modern societies might do well to reconsider ROSCAS as mutual help networks in search of ways of reconstructing communities.