To find this mob in-game, use BACKSPACE to open the World Search window, then enter Watchman in the Search field and click "Search". Remember, the field is case-sensitive and must be entered exactly as shown.
How to get past the Watchman in order to talk to Futen Whitehorn:
You must get a Bottle of Liquor from Soloman Julab at the Merchant's Camp (perform Flavored Liquor) and mix it with the powder in the White Whisper Bloom Medicine Pouch to make Flavored Liquor, a sleeping potion, to give it to the Watchman at the tunnel entrance.
You will need to use the Flavored Liquor sleeping potion every time you need to get past the Watchman to talk to Futen Whitehorn, until you have completed Getting to the Bottom of Things. The Flavored Liquor does contain more than one dose.