Hogback’s exposition: the Zombie General Ryuma “hearkens from the Wano Country of the New World” and, long ago, “slew a flying dragon” — “the samurai of legend” (Ch. 450, pp. 4-5).
The payoff
(status: confirmed — the Wano-legend facet pays off on-page @0937 (≤ window.hi). The deeper Wano backstory — Ryuma’s clan, Shusui’s return / the Enma swap — remains forward.)
Why this matters
Oda routinely plants a legend’s name + a single iconic deed (“slew a dragon”) generations before the payoff. Here it simultaneously seeds (a) Ryuma’s Wano pedigree, (b) his sword’s lineage, and (c) the Wano arc itself — all surfacing well beyond Thriller Bark.