Moustafa (also known as Sheek) is a green Nomadimouse who inhabits Dry Dry Outpost, which he has a great deal of control over, being the leader of a secret group of honorable thieves that dwell within it.
In Paper Mario, Mario, upon arriving in Dry Dry Outpost, learned he would need to have to meet with Moustafa in order to learn the location of the Dry Dry Ruins, where a Star Spirit was being held captive. In order to learn of Moustafa's location, Mario would need to gain information from Sheek, an informant, by offering him items. Once Sheek received a Lemon from Mario he would tell him that in order to learn of where Moustafa was, he would need to go to the local shop and buy a Dried Shroom and Dusty Hammer, in that order. Mario, upon doing so, would be informed by the shop's manager, a member of Moustafa's organization, that Moustafa was located on the highest place in Dry Dry Outpost.
It turned out that Moustafa inhabited a room above a door-less building and that Sheek the information broker was in actuality, Moustafa. Having a conversation with Mario, Moustafa revealed to him that he was a guardian of Dry Dry Ruins, before deciding to trust Mario with the Pulse Stone, which would lead him to the Dry Dry Ruins.
If Mario visits Moustafa after defeating Tutankoopa in the Dry Dry Ruins, he will tell Moustafa of what transpired there. Shocked at the revelation that minions of Bowser were in the Dry Dry Ruins, Moustafa will gratefully thank Mario for having gotten rid of Bowser's influence in the ruins, saying he will be eternally grateful to Mario.
Moustafa, as well as several other Nomadimice, also appear in the parade that takes place after Paper Mario is beaten; during the parade, Moustafa and his companions stop to talk with Rowf and Rhuff before continuing onward. In Paper Mario: The Thousand-Year Door, Lumpy the Ratooey will mention Moustafa while recalling his search for oil in the Dry Dry Desert.
An unnamed Toad in Toad Town, located near the port, will reveal that, having become lost in Dry Dry Desert, he was saved by Moustafa, who brought him to Dry Dry Outpost. It was there that Moustafa revealed to the Toad a large secret, though what this secret was is unrevealed. Additionally, the Wandering Nomadimouse seems to have met Moustafa, as the latter had sent him a letter; where the Wandering Nomadimouse met Moustafa is unrevealed, indeed, the Wandering Nomadimouse only had vague memories of meeting Moustafa at one time.
"This is Sheek. You'd think the guy could shake the dust from his clothes! If I didn't know he was an information trader, I'd say we should steer clear of him. Still, he's our best soure for gossip... As adventurers, we have to deal with all kinds!"
"Da Da Da Duuum! Sheek reveals his true self! ...I guess that means he's the boss everyone talks about. Oh... I was expecting Moustafa to look a lot cooler."
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