The study aims to identify the impacts of population decline on the nightscape of Nagasaki City, which has been acknowledged by tourists as one of three major nightscapes in Japan. In particular, the focus was given to hillside residential areas, which frame the landscape of Nagasaki. The study was conducted by following three steps procedure as a) visualizing the present nightscape by using ArcMap and ArcScene, b) developing scenarios on future population decline, and c) visualizing future nightscapes based on the scenarios. The scenarios developed are based on two hypotheses on the future population of Nagasaki as the decline will occur; 1) equally throughout the entire city, and 2) exclusively at the hillside residential areas because of their inconvenience especially for elderly people. The study identifies that the nightscape following the scenario 1 will become deteriorated compared to the present but still may maintain its character, while the scenario 2 will lead the nightscape to lose its identity. It is therefore concluded that taking measures to suppress depopulation of the hillside residential areas are indispensable to maintain the identity of Nagasaki’s nightscape.
