This paper proposes a computational landscape design method, called the Seeds Scattering system (SS system), that was developed by the AnS Studio to carry out the Sony forest project in Japan.This method enables us to manage various environmental conditions in design processes, to design "natural" in urban areas, ( i.e., people perceive a forest in an urbanized area as if it is natural although the forest is not genuinely natural). First, this paper discusses the limitations of the conventional method of landscape design. In Section 3 to 4, we describes the SS system together with the design process of the project. In Section 5, we present the system from a different perspective, that is, as a method for satisfying social requirements to gain human appreciation.The designer's role in this system is not to manipulate geometries or compositions of tree groupings but to design the fundamental rules that underlie them. As a result, the designer can create a landscape in an interactive manner, thereby producing one that inherently belongs to its site.