Pluck the Piranha Flower

When you first spawn into the level, you'll be on Tiny Island. To get this star, you'll eventually need to be on Huge Island, but it's best to start here. As soon as you get control of Mario, perform a Long Jump to the platform on your left. You'll find a yellow box containing a 1-Up mushroom and a Keronpa Ball.

From that platform, you'll want to Long Jump again to reach the next area, which has a pipe. Be careful here! A Piranha Plant can spawn and shoot fireballs. The area is pretty small, so try to avoid getting hit.

Jump into the pipe. This will transport you to Huge Island, and you'll be in the same general area as before. You'll notice the ground here is a bit damp, which means your jump height and distance are reduced.

On this patch of land, you'll find five Piranha Plants. They're much larger now, even when you're Tiny Mario! Your objective is to defeat all five of them. The good news is that each one still only takes a single attack to defeat.

Once you've taken down all five giant Piranha Plants, the star will appear. Grab it to complete the mission!