Underworld



The Underworld (闇) is the whole system of connections, smuggling and actions which eludes the World Government's control. It's mainly set in the New World.

Organization
According to Law, the New World is divided into territories governed by the strongest pirates thanks to their brokers, pretty similar to a huge crime syndicate. The most influential man in this world is codenamed "Joker".

Due to this nature, the Underworld involves almost all the world main forces and strongest men:
 * Yonko: as the most powerful pirates of the New World, they're involved in the Underworld.
 * Kaido is revealed to be Joker's main customer, via the Smiles smuggling.
 * Charlotte Linlin is revealed to be interested in Caesar Clown's Shinokuni smuggling as customer.
 * Supernovas: as strong New World pirates, some of them has been involved in the Underworld.
 * Trafalgar Law, in order to dethrone Doflamingo, acted as Caesar Clown's alliate. Furthermore, his actions led to the resignation of Doflamingo as Shichibukai.
 * Kid and Killer, even not being brokers, attend to Caesar Clown's presentation of Shinokuni's power.
 * Shichibukai: some Shichibukai are or was involved in the Underworld.
 * Donquixote Doflamingo is the most influential man of the Underworld under his epiteth of Joker.
 * Crocodile, as Baroque Works president, was involved in the Dance Powder smuggling as customer.
 * World Government: due to the World Nobles's involvement, the World Government can't act against the Slavery.
 * World Nobles are interested in the Slavery affairs.
 * Marines: some former Marines got involved in the Underworld after their resignation.
 * Vice Admiral Vergo, as Joker's infiltrated, acted to hide Caesar Clown's illegal actions.
 * Former Scientist Caesar Clown, after the four years ago accident on Punk Hazard, has been involved in the illegal weapons smuggling.
 * Former Admiral Kuzan, after resigned the Marines, could been involved in the Underworld, as Donquixote Doflamingo and Smoker hinted.
 * Two peacefull countries are interested in Shinokuni as customers.
 * The Franky Family previously partecipated to St. Poplar's black market as both sellers and customers.
 * Former Roger Pirates Vice Captain Silvers Rayleigh tried to sell himself as slave in the Sabaody Archipelago's Human Auctioning House.
 * An unidentified Jack has connection with the Brokers and has been informed about Caesar Clown's fall.

Smuggling
One of the main scopes where the Underworld acts is the smuggling via brokers. This involves illegal goods, rare goods, slaves and illegal weapons.

Past
In the last ten years, Donquixote Doflamingo built up his status as the most influential man in the Underworld under his alias of Joker. Due to this, in the last four years, he offered Caesar Clown his protection from World Government.

The Franky Family often sold the products of ships dismantling in the black market.

Baroque Works Saga
Crocodile claims to have obtained the Dance Powder via smuggling. This will cause the Alubarna's civil war. When the World Government discovered it, it deprived Crocodile of his Shichibukai status and jailed him in Impel Down's Level 6.

CP9 Saga
Franky claims to have bought the rare Adam Wood in the St. Poplar's black market.

Whitebeard War Saga
Before reaching the Sabaody Archipelago, the Straw Hat Pirates defeated Duval's Flying Fish Riders, one of the best kidnapping group and slaves supplier of Disco's Human Auctioning House.

During the Straw Hat Pirates' visit to the Sabaody Park the Hound Pets captured Keimi and sold her to Disco. This causes Luffy's rage, his attack to the Auctioning House and the whole Roswald's Incident. Due to this, Doflamingo forsakes Disco and gives him the entire House.

During the Timeskip
Due to Doflamingo's abandonment and the ruckus caused by Luffy, the Human Auction fails.

Trivia

 * Both Donquixote Doflamingo and Smoker indicate that Kuzan may have dealings in the Underworld, though Kuzan neither confirms or denies this.