Zelda II: The Adventure of Link/Hidden Palace

The mystery of Kasuto
By blowing the Whistle, you can create a tune that dispels the River Devil. With the path way open, you can travel to southern East Hyrule. However, as you traverse the mountain path, you will enter sections where Lizardmen ambush you by throwing rocks at you from the cliff tops. In two sections, an Orange Lizardman will also confront you, while in the middle section you will encounter a Basilisk.

Old Kasuto Town
The only obvious sign of civilization in South East Hyrule is the town located at the spot labeled A on the map. There are two ways to reach it. You can take the long way by walking around the lake, or you can take the shortcut by taking the north bridge. If you take the north bridge, you will be subjected to a difficult side scrolling challenge across a bridge with many gaps, and a number of fierce Bagobagos flying out of the water. Of course, you'll have to encounter the same thing when you cross the southern bridge, so ultimately, there's no way to avoid it.

When you cross the southern bridge, you can access Kasuto Town. However, what you'll find is a deserted shambles of a town, with broken buildings, and invisible forces that harm you as you walk around. It turns out that the town is infested with invisible Moas, and you do not yet possess the item that will allow you to see them. If you at least enter the very first building, the man inside will inform you that you should explore the woods to the east.

Exploring New Kasuto Woods
In order to reach the east woods, you must travel through Kasuto Cave (label b on the map). Slightly out of the way is another cave (label a on the map) that contains some fierce enemies and a 500 point bag at the very end. When you enter Kasuto Cave, you may wish to cast Fire so that you can battle the Tektites that occupy the first segment. Lizardmen occupy the second segment. Only enter into combat with them if you truly need the experience points. Otherwise continue on to the exit.

Once you reach the woods, it will not be immediately clear what to do. It turns out that your Hammer can be of some use here. If you use the Hammer on adjacent forest tiles, you will knock down the trees and create meadows. However, inside one particular northern tile, you will uncover the new location of Kasuto Town. Head inside and explore.

You will come upon an old woman in blue who says you deserve her help. Follow her inside and you will find another woman who explains that there is a secret at the edge of town. Further inside the basement of the house, you will find the fourth Magic Container, which will extend your magic meter to eight full bars. Heading back out, you will find another house in the second segment of town with an open door. Inside you will find a fireplace at the end. Push up to explore the fireplace, and you will discover the town's Wizard who will teach you magic known only as Spell. Finally, when you walk all the way to the third segment of town, you will find… nothing. At least, it will appear like nothing. Read the spoiler below to discover the secret.

Investigate Three Eye Rock
Three Eye Rock is another mysterious place in Hyrule. When you travel from Kasuto Town to Three Eye Rock, you will probably have a good opportunity to explore the location labeled 1 on the map. If you do, you will happily discover the fourth and final Heart Container which will grant you eight full bars in your health meter, provided you have found the other three. Three Eye Rock is obviously a location of significance, but once again, it is up to you to discover the mystery behind it.