From a start door, climb the left-side ladder.
When you get to the top of a ladder, you will find two appearing wooden boxes.
Make stairs with them to go toward a door.
Another appearing box is also falling down there.
In order to get a key, arrange the appeared wooden box and go up the upper right bricks floor.
After got a key, go back to the floor where a door is.
Then go up the upper left floor by using a wooden box.
On the upper left floor, a new appearing wooden box will fall.
Drop two wooden boxes (the newly appeared one and the other one next to a shop door) into the lower floor which you reached when you climbed a ladder.
At this lower floor, make stairs with three boxes out of four to the upper left floor.
Swallow the remaining wooden box and go up to the upper left floor with swallowing.
An appearing wooden box will fall down on the left edge.
Put two wooden boxes (swallowed one and fallen one) under a ladder to climb it.
After climbed, go toward the right.
Get through falling boxes and get to a goal door on your right.