Here is a map with all locations of NPCs to speak to highlighted:
Note: Large Dimension Image (Width=16366 Height=2160)
World Map compiled by Gyumaou -
http://steamcommunity.com/id/Gyumaou/Original LowRes Map:
http://imgur.com/BNx1gLuOriginal HiRes Map:
https://dl.dropboxusercontent.com/u/59397071/OTS-Map.tif