From a start door, go down from the left side and get to the floor where many wooden boxes are.
Drop two boxes from the left-side edge and go to the lower floor from the right-edge.
Move up to the left and swallow a cracked wooden box once.
Then release it to your left side and turn it to a normal wooden box.
Swallow again another box near you and drop it to the lower from the left-side edge.
Go down to the bottom and move to the lower left edge of this stage to appear fallen wooden boxes.
You have to go up the upper left floor where a door and many wooden boxes are.
So make a part of stairs with fallen wooden boxes.
Drop boxes above a door to the bottom, and continue to make stairs in the same way, but you have to save just one box.
Climb a ladder above a door to enter a warp door.
When you came out from the upper right warp door, there is a key nearby.
After got a key, continue to collect wooden boxes at the bottom to make stairs.
Use a warp door again and again.
When you came out from the warp door next to a start door, go down to the lower floor where many wooden boxes are.
Drop a box to the bottom from the left-side edge, then go down to the bottom with swallowing a box in order to make stairs.
Repeat the same action until you've finished to drop all wooden boxes.
When you came out from the upper left warp door, drop a box to the bottom from the right-side edge, then go down to the bottom with swallowing a box in order to make stairs.
Repeat the same action until you've finished to drop all wooden boxes.
A door placed on the lower left of a warp door entrance is a dummy door, so you have to go up to the further upper floor.
When you can get to the upper floor above a dummy door, go up the upper right by using wooden boxes.
After that, go up to the upper left to reach a goal door.