This might be a bit too late to help you, if you have already found the ancient temple, i hope this will help others who got stuck at this part of game : you must first get to the place where hirado keep saying 'from here we need to go to the north'(can't really remember what he says

), then from this place you just keep searching for a path which heads north(around the eastern part of this place), where you'll then see two gates when you proceed on to the left, there you'll see a fireplace-liked 'hole', enter it. Just remember that you don't leave the place where hirado mentioned the instruction and try to get to the top most part of that place. Good luck!