The left hand picture shows what it might look like folded up. Some of the slots could have drawers for storage of clothes, while others can be left open for books.
The right hand picture shows how it will extend into a stair case. Each step is mounted on a pivot on its right side, and will interlock with the next step so that it can be opened and closed by moving only the top step. I will need to work out some sort of rope or gear mechanism to operate it.