The Riariti Historical Society, or RHS, is a guild created by scholars who wished to learn more about Riariti's mysterious past. Consisting of many races and cultures who have all gathered to learn, the RHS is supported by donations from all over the world in the hopes that more knowledge can be discovered.
There was a terrible war 8547 years (as judged from the start of the comic) in Riariti's past in which much knowledge regarding history, magic, and item crafting was lost or destroyed; this is known as the Lost War. Items from before the Lost War are known as Legacy Items and are incredibly valuable. The RHS will pay exorbitant amounts of money to get hold of one in order to study it and hopefully increase the amount of "modern" knowledge available to Riariti's inhabitants. Once they have gleaned as much information as possible from the item they turn around and sell it to adventurers for a lowered price.
RHS guild facilities are available in large cities, but they can be contacted via Maike-mail if you find a Legacy Item and wish to sell it to them.
Sometimes regular items that pertain to before the Lost War can be found in dungeons or ruins. These items were often created by the Ancients, and if they contain unknown knowledge they can be worth almost as much as Legacy Items. Of particular value are intact books or records.