Structural lore — the New World’s secret criminal economy of brokers and black-market dealing. First named on-page Ch. 698 (p. 14).
What we know
Ch. 698: explained on-page by Law (p. 14) — the greatest pirates rule territories “like an enormous criminal syndicate,” and all their “necessary deals are conducted in secret… in the underground” to avoid naval attention.
Ch. 698: the most trusted and powerful of these brokers is Doflamingo, whose underground alias is “Joker” (p. 14).
Ch. 698: Joker’s largest current client is the Emperor Kaido — the SMILE trade (pp. 14–16). Establishes the broker / black-market layer connecting Warlords, Emperors, and Devil-Fruit / weapons dealing.
Ch. 732: An entire hidden underworld trading port (“like a gigantic PORT TOWN,” p. 19) operates beneath Dressrosa, run on “JOKER” (Doflamingo) backing — a concrete depiction of the broker-and-trade layer of the world’s underworld economy. The transformed toys are its forced labor force. See Dressrosa Underground Trade Port.
Chronology / structure
The underworld supply chain as framed @0698: Caesar (manufactures S.A.D.) → Doflamingo / “Joker” (broker; turns S.A.D. into SMILE) → the Emperor Kaido (buyer, building a Zoan army). The broker tier sits hidden beneath the visible Warlord / Marine order.
Open questions about this topic
The full membership and reach of the underworld broker network (only Joker is named @0698).