In this paper I will discuss two constructions of the Japanese verb aru ‘be’. In one construction, aru occurs with a copular complement marked by the particle de, obtaining a sentence-ending pattern known as N-dearu. In the other construction, aru expresses the happening of a dynamic event and may occur with a de-marked locative adjunct encoding the physical place of the event. By analyzing these two constructions I will single out a ‘predicative’ function of the case marker de, and show that when functioning as a support item in nominal predications and in other copular sentences, aru retains its original nature as a locational verb and consequently assigns a locative-like grammatical case (marked with de) to the second argument of its clause. In this instance of strong localism, a grammatical split of the locative marker de happens so that de ends up marking a number of different surface cases. In the conclusion I will propose that the particle de in predicative function should be acknowledged to be an ‘Essive’ case marker.