Um...wow. We're filing this under "if we lived in a huge loft and were married to a carpenter." But that doesn't mean we can't admire it. It's is an igloo-like structure with books for walls, a felt roof and containing a sleeping nook. See more photos below...
At first we thought this must be a concept design only, but it appears it was actually built as part of a full renovation of an apartment in Japan by Point Architects. Since there were no supporting beams in the middle of the space, the owners decided to have all the beams and partitions taken down to create a large open space. They call the structure the Uroko House and while not designed specifically for children, we imagine any child would love this cozy, hideout for a bedroom.