This paper deals with the phenomenon in which wa appears in Japanese conversation without preceding phrases (hereafter referred to as Bare-wa). I will show that the phenomenon raises fundamental questions about wa as a conventional topic marker, and then I will propose a new analysis of the phenomenon. I argue the specific function of Bare-wa in the discourse, which is not seen for case particles, on an assumption that Bare-wa is identical to topic marker wa, and that the utterance-initial wa, especially, acquires an interjectional function because it is inspired by a focuspresenting function indigenous to its topic marking usage.