Engineers have little time for requirements elicitation and their validation, because they still have to make great effort to write down concrete use cases. Though concrete use cases are important to derive test cases, it is possible to free engineers from the routine work of defining similar use cases repeatedly and at the same time keeping consistency in requirements elicitation. Here, we propose one of the solutions concerning these difficulties. The requirements description metamodel called RD-metamodel integrates the activity graph metamodel and the use case metamodel. It supplies a mechanism of the use case writing with multiple perspectives: the resource reference perspective, the resource-structure perspective, the activity, sequence perspective, the process perspective, and the actor's perspective.