After you defeat Broken Joe in the first cave, you pass through more ruins and enter the second cave of chapter 6.
Explore the Cave
Don't go north. Instead, go east through the wall. Jump on the third tile from the bottom to make a switch appear. Jump on the switch, then go north through the door. (The tile to jump on is marked with an O below.)
DOOR x x x x x O x x
Kill the Rattus to open the north door. Go through.
Beware of the blades that come up from the ground toward you. Move out of their way to avoid getting hit. Kill the Noctos to open the north door. Go through.
Jump north on the tiles to get the Shuriken in the middle of the room. Press SELECT to switch to it, or press START and use the directional pad to switch to it, then throw a Shuriken north, then press the attack button again to make it split in two to hit the two Loopers. Do this to kill the rest of the Loopers, then go north through the passageway.
Throw a Shuriken and press the attack button again to make it split in two and kill both Loopers. Then stand to the southwest or southeast of the spiked ball and throw a Shuriken north, and press the attack button again to make it kill the two Loopers there. After that, use the Star/Yo-yo to hit the spiked ball, and jump over it, then go north through the door.
If you don't want two double hearts, skip to the next paragraph. If you want two double hearts, kill the flies. You can try using a Shuriken to kill both flies at once. When they're gone, the west passage will open. You can go through it to get two double hearts.
In the room where the flies were (or are), jump on the middle tile on the left, then jump on the switch, then go north through the passage.
Kill Noctos until the door opens, then go north through the door.
Avoid the floating orbs. If they hit you, they make you temporarily unable to use weapons. Kill the purple fish to make a west passsageway open. Go through.
Go north and jump across the water in the north passage to reach the next room. Then go to the left so you're up against the water, then go south and jump over the water to return to the previous room in a new location. Go around the U shape and get the double heart, but don't jump north over the water this time. Instead, push against the middle of the west wall until you go through. Get this double heart, then go north and jump over the water. Go to the north wall, stand in front of the middle tile of the wall, then walk south. You will fall through a hidden hole.
Go to the south side of the room and jump on both of the southern tiles, then step on the switches to open the treasure chests. Take the Magic Potion and Shurikens that appear. Then jump north or south to get off of the island, and go up the stairs.
Go south and jump over the water, then jump onto the tile, then jump on the switch and go through the door.
The Hoodoo doll will walk toward you, and if you're in its path, it will shoot orbs in each direction. If you stand north or south of the doll, but one square to the left or right of its path, you can use the Shuriken (without pressing the attack button a second time) to hit it without danger of getting hit. Or you can hit the Hoodoo doll then immediately walk to the side to avoid the orbs. Run away if the Hoodoo doll gets too close. After it's gone, jump on the tile to make a Try-your-luck sign appear. If you take it, your extra lives will increase or decrease by a random number. Afterward, go north through the door.
Jump on the southern middle tiles, and the southeast tile, to reveal a double heart, a shuriken, and a switch. Collect the items and step on the switch, and jump on the tile to the right of the switch to make another double heart appear. Take it and go through the north passage.
Turn to the left and use a Shuriken, then press the attack button again to make it split in two to hit the Looper to the north, then turn to the right and do the same thing to hit the other Looper to the north. Then hit the spiked ball and jump over it, and stand on the narrow platform that sticks out to the left to throw a Shuriken north, then stand on the narrow platform that sticks out to the right and do the same thing. Then go through the north door.
A clay monster will dig through the floor. Avoid the shards of rock that appear above where the monster is digging. Then the monster will pop out of the ground and shoot stones in all directions. As soon as it pops out of the floor, jump to avoid the stones that it throws, then hit the monster. Do this until it is gone, then go north through the door.
Kill the flies to open the north passage, then jump on the leftmost tile and rightmost tile to make a Shuriken and double hearts appear. Take them and go north.
This room has two clay monsters. Move out of the way of the piles of dirt, jump over the stones that they throw, and hit them. If the monsters are not coming out, move around the room to get them to appear. After they're both defeated, go through the north door.
Avoid the blades that come out of the ground, get the double hearts if you wish, and go through the north door.
Throw Shurikens at the monster in this room. If you run out, go west through the wall and jump on the tile to get more. After you defeat the monster, go through the north passage.
Ignore the monsters and go through the west wall. Jump on the middle platform, then jump south to the next room. Jump on both tiles, then take the Magic Potion and the Shuriken, and jump on the switch. Go through the south door.
Kill the two Hoodoos like before. Then go through the west door.
Step on the tile, then step on the switch, then go north through the door.
In this dark room, you can go through the west wall somewhere near the middle. Jump on the tile in front of the treasure chest, then jump one tile west. From there, jump south until a switch appears to the right. Jump south again, then east to get the double heart, then step on the switch, then jump north and take the Shurikens. Then go east through the wall again, and finally, go north to the next room, where you will battle Twin Sumocho.