The retractable hardtop system is an ultimate roof system that offers both convertible and coupe-style modes. Passengers can enjoy open-air driving with the convertible mode, and a comfortable and quiet cabin space with the coupe-style mode. Aisin Seiki developed the retractable hardtop system for the LEXUS SC430 in 2001. We developed the three-piece retractable hardtop system, which was further improved with the LEXUS IS250C for the global market. This paper introduces the structure of the roof system.