Jadusable is the main character and initial author of the "Haunted Majora's Mask Cartridge" story. His real name is Alex Hall; Jadusable was the username used to post the story on 4chan, and so that is the name he's referred to as. He is a sophomore in college at the start of the story (September 2010) and is presumed to be 20 years old due to this and the fact that he states he's not old enough to drink.
His computer and its online interactions are progressively taken over by BEN during the course of the story. Based on information inferred from his final Youtube video, he is presumed to have been trapped inside the cartridge by BEN.
As of recent 2017, he has been minorly active with his YouTube.