(Historical note — now superseded by the confirmed callout above. Pending — payoff is forward of this window. The full name “Rocks D. Xebec” and the God Valley specifics land ~Ch. 957+; the Rocks-crew survivor reveal and the Big Mom/Kaido shared-past origin are forward.)
Xebec” or God Valley details.
Earliest known caller
(Not researched.)
Why this matters
A throwaway-seeming name-drop carries a whole hidden era: Oda plants the Rocks Pirates as the load-bearing backstory of the Yonko system and Garp’s reputation ~50 chapters before naming Rocks D. Xebec, fusing a single dialogue beat to the World Government’s deepest fear of a returning era.