Go to the second floor with the ladder and open the elevator door.

Start the elevator with the iron rod stuck into the drainage outlet.

Open the book and go to the imperfect world with the elevator stopped in the middle.

Enlarge the book and go to the world inside the book again.

If you go to the second floor with the ladder and open the elevator door, the elevator will serve as a foundation for you to go to the rear.

Pull the lever on the right side to lower the chain.