The Contiguous Building Design System makes possible the applied multiple building lots to be recognized as a single site in the building standard law. Its utilization is anticipated for improvements in the densely build-up residential area. In this study, the regulation of Kawasaki City is examined in comparison with that of other municipal governments. In Saiwaicho-Sanchome district, multiple tactics for a typified site and simulations to an existing site are conducted. Through the comparative case studies in multiple levels, characteristics and potentialities of the system are pointed out. Then, further development of the system in such area is examined.