Japanese Puzzle Box

I've had this little box since I was a teenager. I've had a thing about collecting boxes, which no doubt one can read all sorts of things about my personality into if one is of a Freudian bent.

Although the box looks perfectly smooth, certain panels slide one way and another. After a certain order and number of moves (in this case 9) the box opens to reveal a small inner space.

I keep dark secrets inside.