The challenge of the requirements engineering to digital consumer products lies in that the users are unknown many of wide variety. The major contributions of this article include a technique to identify persona to provide a rich contextual model of a group of primary targeted users based on conjoint analysis theory, and a technique to identify the value and hot spots in the requirements through the interaction analysis between personas and scenarios. We applied the proposed methodology to mobile phone product lines through a series of field studies conducted with more than 150 users from 2003 to 2004 in Japan. The studies revealed the various aspects of non-technical users, and proved the effectiveness of proposed methodology in the requirements engineering for digital consumer products.