Rotating Savings and Credit Associations (ROSCAs) are common throughout the world and were widespread in Japan. However, with the exception of the Okinawan Moai (ROSCA), most Japanese ROSCAs fell out of practice with the development of competing financial institutions. In Okinawa, "social Moai" which is not for financial purposes but for developing close relationships with friends or acquaintances, is most popular. This paper examines three social Moai groups in Naha, the prefectural capital of Okinawa, to clarify the features and roles of social Moai. Social Moai in Naha not only strengthen existing bonds but also tighten fluid relationships. The people of Naha try to sustain different types of social Moai such as a Moai of alumni belonging to the same age group and a Moai of friends from different backgrounds and jobs. In this manner, people are able to maintain a wide variety of human relationships. This study also reveals that Moai members sometimes help each other both officially and privately because they are members of the same Moai. Social Moai is not a group of mere amusement or recreation but a mutual help association, which keeps up the traditional Okinawan spirits of mutual help.