This game has a hidden "anything" at least up to twice a map or house, or in some cases (like the castle) once or twice a room. In fact, for example, there is a well you can enter right before you go to the Mage's (broken)house in Pao ...that gives a kunai. This most of the time doesn't even include the books you can find , shining items, chest or the skill orbs. Also for people who don't know where some things are early, it is in the actions in inventory.
Also remember that controls screen in the beginning?
Q is history, W hides text box, S is mini map, A is full map, Z is action, X is menu. ctrl /enter to skip. All the "or" are actually saying the number pad keys(including /,*,-,+ if you have them) , the arrow keys or num 2/4/6/8, and Mouse buttons. F5 to refresh the game to title screen as usual.
Of course, this is for people actually playing the game
like me.