Labyrinth (Famicom)/Area 9: Terror Maze
The only enemies that you will encounter in this area are the Trashing Machine. Sarah will lose a significant amount of time if she gets hit by them, so avoid them at all costs. When it passes below Sarah along a vertical passage, hit it with a stone to stop it in its tracks, and head upwards away from it to a safe locations. No more than two Trashing Machines can appear on the screen at one time. You will obtain another set of three coins by this stage. Presumably, you have purchased both defense increases, so now you can improve your offensive power by buying the Bead Ring.
There are a set of stairs beyond the key which take you to the isolated corner of the first area where you can find a collection of bonus items. You'll need to use the Crystal Ball that you find there to warp out and visit the Wiseman. It's difficult to reach this area without collecting the key, which warps you out of the area. So in order to visit this staircase, you need to leave the coin behind so that you can warp back to this area, visit the staircase, and then warp back in a third time to collect the coin.