After I used the that drowned potion and talked to that guy the game bugged. In the walktrought the "who is Derrida?" dissapeared and other item apeared, but in my case nothing happened.
I dunno if it is a bug or something else but then I gave reptile sellsman a sand fruit I didn't get any special oinment. Well the game wrote that I got it but I can't see it in inventory. I did the quest after I killed the mysterious guy.
 "Thousand Dollar Soul"){kind=icon}
 "The Trader of Stories"){kind=icon}
 "Monster Slayers"){kind=icon}
 "Book of Mages: The Dark Times"){kind=icon}
 "Dream Tower"){kind=icon}
 "Reincarnation: Let The Evil Times Roll"){kind=icon}
 "MARDEK RPG: Chapter 3"){kind=icon}
 "GrindQuest Beta"){kind=icon}
 "Protector IV"){kind=icon}
 "Loved"){kind=icon}
 "Naruto Ultimate Quiz"){kind=icon}
 "chest pusher"){kind=icon}
 "Red"){kind=icon}