After you acquire the Speed Booster ability from the yellow E.M.M.I., you return to Artaria.
Get an Item Sphere
Shoot the Wide Beam Cover on the left, then shoot open the door and go through.
Go upward and to the left until you are on a T-shaped platform. Jump up onto the ledge on the right, then go to the right until you are far enough from the left edge that you can charge up a Speed Boost. Speed Boost to the left, and jump over the gap to break through several sets of Speed Booster Blocks. In the next room, tilt the left control stick down to ready a Shinespark, then center yourself in the room and press B to Shinespark upward through a number of beam blocks. (If you're having trouble with this, you can just shoot your beam upward at the beam blocks to break open the path.) From the top of the room, go through the door on the right to reach a Save Room. Save if you wish.
From the Save Room, go through the door on the right. Go right again and drop downward to the bottom of the room. Go through the door on the right, then drop down to the lower level and shoot a missile at the bottom right door, then shoot it again to open it. Go through.
Go to the far right side of the room and shoot the Item Sphere to get the Grapple Beam.
To use the Grapple Beam, hold ZR to switch your arm cannon to Grapple Beam Mode, then hold Y. The Grapple Beam takes a moment to extend from your arm cannon, and will be deactivated if you stop holding Y. While still holding Y, you can tilt the left control stick in the opposite direction to pull open Grapple Beam Doors, destroy Grapple Beam Blocks, and move Grapple Beam Boxes. In addition, you can use it to swing from Grapple Swing Points. You can shoot also the Grapple Beam at magnetic walls and hold Y to be pulled to the wall.
Return to Dairon
Go to the left, then hold ZR and Y to latch onto the Grapple Beam Box. Tilt rightward on the left control stick until the Grapple Beam Box is pulled into the gap. Jump up onto the ledge on the left and hold ZR and Y to latch onto the door. Tilt rightward on the left control stick until the Grapple Beam Door opens.
In the next room, hold L and aim at the Grapple Swing Point in the ceiling, then while still holding L, hold ZR and Y to latch onto the swing point. While still holding ZR and Y, you can tilt leftward and rightward on the left control stick to increase your momentum as you swing. If you fall off, you can just aim at the Grapple Swing Point and hold ZR and Y to pull yourself back up and try again. Swing to the upper left door and let go of the Y button to land there, and go through the door.
In the next room, jump up onto the ledge, then aim at the magnetic wall and hold ZR and Y until you are pulled onto it. As you go upward, keep in mind that you can hit the creatures on the wall with the Grapple Beam to kill them. Use the Grapple Beam on the magnetic walls above you until you reach the top of the room. Go to the left and go through the door to reach an elevator area. Stand on the glowing panel in front of the elevator to go back to Dairon.
Go to the Next Area
Use the Grapple Beam to pull on the Grapple Beam Block on the right until it is destroyed. Then enter the tunnel and drop a bomb to activate the Morph Ball Launcher.
At the other end, you can optionally go through the door above you to save the game. Then leave the save room through the door on the left. Jump up onto the ledge on the left, then go through the E.M.M.I. Zone Door. If there are still Speed Booster Blocks above you, Speed Boost or Shinespark through them. Go through the upper right E.M.M.I. Zone Door.
Go to the right and jump up onto the ledge, then use the Grapple Beam to pull the box toward you. Go to the right and upward, and use the elevator. It will take you to Ferenia.