Once the gates are open to the next spark pylon, go through them and turn left. Head straight to the western wall and jump up while hugging it to reveal some hidden coin blocks. Use these to reach the ledge above, then the roof, where you’ll find three purple coins (39) right there, as well as a Power Moon on the other side (From the Side Above the Castle Gate) . Take the spark pylon to arrive on a small island with the souvenir shop. You can purchase a moon from the yellow shop (Shopping at Bowser’s Castle) , and you’ll also want to buy the complete Samurai outfit from the purple shop for 15 coins (change into them).
Exit and go around to the back of the shop to find a man with a samurai helmet guarding a locked door. Before you speak with him, backflip onto the roof to find a small hole with three purple coins (42) . Drop back down and speak with the man with the Samurai outfit on to unlock the door, so head inside. Enter the pipe to make an 8-bit mural appear, with the first area containing nothing. Note that the mushroom platforms will sink into the ground when standing on them, which will be the main point of this mural.
The second area is more of the same, although you’ll need to wait for a moving platform on the right side to get into the pipe. For the third area, you will see a note in an alcove in the middle, accessible only from the bottom, as well as a Koopa Troopa on top of the central platform. Leave it alone for now and use the moving platforms to reach the note. Collect the ones on the left side, then hit the Koopa shell to the right to get those and get another Power Moon (Taking Notes: In the Folding Screen) . The final screen will have a large mushroom platform in the middle, a Koopa in the upper right, and the moon/exit pipe blocked off by some bricks. Hit the shell onto the mushroom platform and use your weight to push it down enough so it can break the bricks on the right, allowing you access to the the moon (Scene of Crossing the Poison Swamp) and the pipe.
There are two more moons on this tiny island, both requiring you to capture something. On the side of the shop are two statues, which you can rightly capture. The Jizo statue can only move, which you can speed up a bit by moving and holding down the Y/X button, and does nothing else. Look in the sand garden and you should notice that a statue is missing in the row there. You will have to line up the statue, so it will need to be facing forward. Once you get it into place, a Power Moon will spawn on a nearby rock (Jizo All in a Row) . Grab the same statue or the other one and look for the lone tile next to where the previous moon spawned. You can break through this tile with the statue, where you’ll find another line of statues, earning you another Power Moon (Underground Jizo) .
Once you’re finished here, take that other spark pylon to a new area, where you will see two small arenas. These arenas will pit you against rematches of two of the Broodals, but there are some things to do before confronting them. There are two buildings near where you land, with the northwestern one having thre epurple coins (45) and the southeastern having another spark pylon. This will send you to a small island with three Stairface Ogres on it. Destroy all three of them to acquire a Power Moon (Exterminate the Ogres!) . Return to the main area to face down some Broodals again.
When facing the moon pedestal, the arena on the left will pit you against Harriet again. She is the same as last time, except she has two bombs she’ll toss at you, in a slight V-shaped pattern, so you will need to do a little bit of aiming to reflect them back at her. After finishing her off, head to the other arena to refight Topper. He’s a little bit more challenging than in the first fight, as he’ll spawn more hats in between each phase. Also, on the second and third phases, Topper will have a huge stack of hats on him and you can’t remove them all before he’ll do a spin attack. Note that the range of his spin attack is telegraphed, plus you can also damage him by jumping on him during it. Defeating both Broodals will net you a Power Moon (Big Broodal Battle) .