The Ryukyu (Okinawa) Islands are situated in sub-tropical zone between the Japanese Archipelago and Taiwan. Although Okinawan people have a rich tradition of star lore, few studies have been undertaken on its relevance to subsistence, religion and the socio-political system. This paper is a first attempt to explore a systematic relationship between star lore (e.g. relating to the Pleiades) with agriculture, fishing, navigation and religious practice. This paper also considers the possibility of interpreting the nature of prehistoric and historical stone structures from the viewpoint of archaeoastronomy. This kind of analysis is likely to be fruitful, since the kingship of the Ryukyu Islands was strongly associated with sun worship.