Drawing on natural conversation data obtained through field work, this paper explores a passive used as an unmarked voice (e.g., You will be hit now vis-a-vis the expected I will hit you now) in certain discourse contexts in Okinawan, an endangered sister language of Japanese. This passive, termed here as "strong warning passive," occurs in a speaker-addressee dyad at the speech time, like a performative sentence, but unexpectedly only in passive voice. After pointing out necessary conditions for such passives, further recognizing futuritive "weak warning passives," and bringing in baseline regular passives, this study points out gradational changes in the three passives along three dimensions: speaker involvement, spatial/temporal distance from the deictic center, and agent explicitness. Lastly, the paper offers an explanatory account as to the existence of the warning passives, drawing on typology (become-language) and the addressee-orientation. (C) 2020 Elsevier Ltd. All rights reserved.