- "Wonder why this place isn't slagged like the others that they've found? Maybe they were wiped out by some kinda germ warfare attack?"
- ―Han Solo
Seoul 5 city was an abandoned city on the planet of Seoul 5. It was the only known intact city of the ancient Seoularians. Although all other Seoularian ruins had sustained massive damage in an apparent comic war, this city had been kept perfectly intact. Han Solo speculated that this may have been due to a germ warfare attack which had kept the buildings intact. The center of the city, Onrai square, contained a statue of Mother Goddess Onrai. Under the city center was the crystal control room, a location that was the source of power to the city due to its stash of Seoularian crystals. However, the removal of the Key crystal by an Imperial scout shut down the city's power.
Before the outbreak of the Galactic Civil War, an Imperial scout inadvertently discovered Seoul 5 and the city following a Hyperspace accident. After exploring the city, the scout discovered the crystal control room and the stockpile of Seoularian crystals contained there. Before departing, he removed the main key crystal and brought it back to Imperial space with him.
Following the Battle of Endor and the death of the Emperor, Captain Drezzel came to Seoul 5 and began to explore the intact city. Using two Xenoarchaeologists, Xathan and Fem Nu-Ar, the Imperials began to document the city, including the crystal control room. At the same time, the Imperial scout who had discovered the city lost both the key crystal and the coordinates to Seoul 5 to Han Solo in a card game. Solo and his copilot Chewbacca made their way to the city and were immediately confronted by Drezzel and his adjutant Ssssk!. Solo was able to make his way into the crystal control room and rescue Xathan and Fem Nu-Ar, who had been imprisoned by Drezzel when they objected to using the Seoularian crystals as weapons.
In their ensuing escape back to the Millennium Falcon, Solo jammed the key crystal into a control table containing several other Seoularian crystals. The action caused a huge outpouring of energy, threatening to destroy the ancient city. Solo and the two xenoarchaeologists made their way back to the ship and fled off planet. Although Drezzel sent several TIE fighters in pursuit, the energy from the crystals caused a massive explosion, destroying the city and pursuing Imperial ships. Although the xenoarchaeologists lamented the loss of the knowledge that had been destroyed, they were content to know that the Imperials would be unable to use the Seoularian technology to create advanced weaponry.