Longshore

Longshore is the greatest city on Mercury, located underneath a gigantic crater located on Mercury's Terminator Line between the "day side" and "night side" of the planet. Through a marvel of ancient technology, the crater is sealed in by a dome known as the Celestial Shield, which keeps the atmosphere in and harmful radiation out, but parts to allow starships in, and then reseals itself behind them. Day and night cycles are simulated by gigantic rotating polarized filters.

The Longshore Underworld is the largest of any on Mercury, consisting of an enormous cavern some two hundred miles in radius, and with a ceiling nearly two miles high, with a shallow ocean - the Underground Ocean - some 30 feet deep stretching across its floor. Several islands dot this ocean, the largest housing the city of Longshore itself. The tallest spires to be seen in the city would be the Cathedral of Longshore and Lord Moya's Palace.

A series of elevators - each broad enough to hold several starships or a small army of soldiers - connect the city to the dismal area below known as the Undercity, from which the Webways may be reached.

Other islands include:

Fukido

Overlord Kayi, great-grandfather of the current reigning Overlord, sought to undermine the power of his son, Nakamura, by building a port city to rival Longshore, located directly opposite it, on the other side of the planet, along the Terminator Line. Kayi opened up the city to any who could afford the space - even off-worlders, provided they could afford the inflated prices. Imperial was quick to jump at the chance, and used a variety of holding companies and off-world deals to buy up - in secret - 98% of all the available space, using corruption, bribery and intimidation to get its way. Mishima woke up to find that a corporation had finally gotten a toe-hold on their previously closed world, and they protested, but the Cartel upheld the legality of the arrangements, and the Brotherhood negotiated a peace between the two parties - the lease, after all, would run out in 99 years, so Mishima need only wait.

Imperial knows that its days are numbered, and has made Fukido into the most free-market capitalist environment one could imagine, in hopes that once the lease expires, Mishima would be reluctant to try to take Fukido back after so many years of freedom. Lord Moya has been tempted to push up the schedule and take Fukido back a bit early, as Imperial has used Fukido to stage any number of illegal operations in Mishima lands, but Imperial has made it very clear that they will fight to the last man if it comes to that ... and by way of appeasement, Imperial makes a point of raiding the holdings of Moya's rivals, Lord Heir Maru on Venus and Lord Heiress Mariko on Mars.

There is no enforced law in Fukido, and corporate interests are expected to keep the peace on their own properties. For the most part, this works, but there are still some places in Fukido where you don't go without several friends and a lot of weaponry and ammunition. Nonetheless, minor corporate interests flock to Fukido for a chance at the big time, and the number of legal entries into Mercury rival that of Longshore. (The number of illegal entries into Mercury are several times that of Longshore.)

Akirenko

Akirenko is a prime example of the dirtier, grittier side of Mishima society. The Underworlds of Mishima are supported by Undercities, where Commoners labor to support ancient machinery in dreadful conditions. Entire families live virtually chained to the machines where they work, never traveling more than a mile from their work stations during their entire lives. Those who can afford it buy air filters to avoid breathing in the toxins from the polluted air. Those who can't ... live short and miserable lives. The people are kept from revolting by patroling Samurai who keep the peace, and the people know that the Samurai will deal swift punishment in the form of death for anyone who makes the slightest infraction.

Akirenko is one such Underworld, where the upper class live in cities built on great platforms suspended from the sky-ceiling far above, tethered to the ground by massive cables that serve to send fuel and supplies to the cities. The people in the cities above toss their refuse over the side, and many peasants walking the streets below die from plummeting debris. The lowest of the Faceless live by scavenging the junk dropped from above.

Cybertronic has extensive dealings with the well-to-do of Akirenko, and experimental cybernetic enhancements are in wide use here - so much so that cybernetics are amongst the junk tossed down on the heads of the peasants below. Many of the peasants have taken to being fitted with clunky, unreliable cybernetics, using scavenged technology, in order to make themselves better workers, and there are even some Black Adepts who have delved into the forbidden technologies of the Thinking Machines.