The present study investigates the ways in which Japanese speakers negotiate their opinions in conversational interaction. On the one hand, speakers are apt to exaggerate a particular aspect of a given issue in asserting their opinion, on the other hand, they may also incorporate a self-qualification admitting a potential problem in their claim. By expressing their awareness of the problem before it is pointed out by the co-participants, the speakers seem to get license to proffer an exaggerated or overgeneralized claim and to increase their chance of receiving an affiliative response. This study explicates the mechanism through which such a self-qualifying clause emerges in the development of opinion-negotiation sequences. Further, as a contribution to a growing body of research on "interaction and grammar" (Ochs, Schegloff, and Thompson, 1996), this study explores the use of "contrastive" markers, -kedo and demo, in constructing turns and sequences in opinion-negotiation. The data demonstrate these two structurally different types of markers play distinct roles in differentiating and yet conjoining the speakers' assertion and self-qualification.