I ran into a weird situation, and I thought it may have been a hidden quest. I attack some bandits late at night between Haringoth Castle and the mountains immediately to the west (in the mountain range.) The display mentioned that camp bandits have joined the enemy for the battle. I didn't see another party in the area, but whatever. At the end of the battle, there was a dialouge with an "unarmed troop" saying his clan would not forget and seek revenge against me (the same kind of crud mercenary field generals say when you defeat them.) I have no idea who he was or what clan, and I really didnt need any more enemies at the moment, so I let him go.
After I let him go, it went back to the map, and there was still nothing on the map showing him or his party. I never found him again, even when I quit and restart the game to have it happen again. I regret not taking him prisioner!!
Also, I found a hidden treasure chest in one of the cities. It has a Ronin Mask and a Nodachi Sword. Good stuff to grab at the beginning of the game!
So maybe there are hidden quests.........