Erra is an NPC created by the GM Rare in an attempt to have a character they can use to play the game whenever business became slow. He levels as her and uses her as basically an alternate character.

Since NPCs in this game aren't players and can't be registered as players, she's considered to be a fodder adventurer, an npc who plays the role of adventurer to fill the gap in parties, and Rare uses this to his advantage to see how players interact in the world. The TOS of his job states he's not allowed to make an actual player character, so he found a way around this rule when GM's were given the ability to create their own monster toon to play.