“Focalization” is a narrative discourse technique that produces different narrative structures based on choosing unique perspectives from which to present a story. This study designs a focalization mechanism and presents an experimental implementation. The proposed system functions as part of our integrated narrative generation system (INGS). In addition, the approach computationally extends the conceptual research of focalization by Genette to techniques for narrative generation. We define focalization as a procedure to transform a story structure into discourse structures through the following two steps: 1) restricting the scope of story information perceived from a chosen perspective, and 2) generating a discourse structure based on perceived story information. In particular, we define two types of rules for restricting the perception scope based on: a) objective perceptible possibility of constituent elements in a story and b) situations or states in which constituent elements in a story are positioned. Based on the experimentally implemented system, we present generated examples from a story using different focalization types. Through analysis, we show that the basic function of the focalization mechanism was achieved by the aforementioned rules.