This paper proposes Persona-Scenario-Goal (PSG) methodology as an extension of Persona-Scenario methodology, and its empirical study in the usercentered requirements engineering for a Web application system. The Persona-Scenario methodology demonstrated the effectiveness in capturing requirements of consumer products, such as mobile phones. However, the methodology has limitations to evaluate the multiple, possibly conflicting, requirements. The PSG methodology intended to identify a set of value requirements from multiple and even conflicting requirements by combining persona, scenario and goal-oriented techniques. This paper discusses the model and procedure of PSG methodology, and demonstrates its effectiveness by applying the methodology to reengineering a Web application system.