System developers often create design documents using various UML design tools. Extant tools, however, have a serious drawback. They fail to capture relationships inherently existing among design documents such as sequence, state and class diagrams. This drawback may not only disallow developers to freely navigate the relationships, but also make it difficult to automatically enforce the integrity constraints derived from the relationships. To overcome this, more sophisticated tools for facilitating the analysis of the documents are necessary. These tools may be used to understand and verify the whole process of the system by defining relationships between documents and providing efficient navigation methods. In this paper, we developed a navigation tool that enables developers to systematically analyze systems by capturing relationships such as duplication, instance, and transition between documents. In contrast with the navigation facilities of other UML design tools, this tool makes it possible to navigate not only design documents but also design elements. In other words, it can systematically capture and verify both the static structure and the dynamic behavior of the system in more primitive level. To provide such a facility, we addressed the practical issues and formulated a solution for them. The issues that were mainly discussed were the following: 1) definitions of three relationships: duplication, instance, and transition, 2) assignment of relationships to related design elements according to the predefined way, and 3) presentation of a set of functions to navigate them.