Thank you for you answer :D, I manage to followed most parts and adding switches. However, I still cannot get the guard to disappear. Although, the chat dialogue no longer appear (after the assassin is killed). What do you mean by "Add another page, and select the self switch to be ON. (Also make sure the next page doesn't have any graphics, this will make the NPC disappear.)"?? I added an event under "branch end" called control "self switch A = ON" however it doesn't seem to have any effect and there is no graphic option either. (My NPC is visible)