In this paper, a style design system in which the conditions for Class A Bézier curves are applied is presented to embody designerâTMs intention by aesthetically high-quality shapes. Here, the term" Class A "means a high-quality shape that has monotone curvature and torsion, and the recent industrial design requires not only aesthetically pleasing aspect but also such high-quality shapes. Conventional design tools such as normal Bézier curves can represent any shapes in a modeling system; however, the system only provides a modeling framework, it does not necessarily guarantee high-quality shapes. Actually, designers do a cumbersome manipulation of many control points during the styling process to represent outline curves and feature curves; this hardship prevents designers from doing efficient and creative styling activities. Therefore, we developed a style design system to support a designer âTMs task by utilizing the Class A conditions of Bézier curves with monotone curvature and torsion.