This paper proposes a support tool for designers who have realized the potential benefits of using a scenario-based approach, yet need a more concrete guidance for its implementation. As an informal framework for scenario creation and use, the tool supports three areas: (1) documenting the large amount of design information, (2) making sense of and summarizing the information by creating scenarios, and (3) sustaining an integrated use of the scenarios throughout the design process. By making explicit and supporting the process of using scenarios, we expect that designers can better structure their design information, communicate their ideas and confirm their rationales. Our ongoing work includes the verification of the tool concept and the development of a testable prototype.