This is the 3rd one of the Byway Secret series.
For the present, maybe it's the last one of this series. I name it another name, "Wrong side secret." You can't see the decoration on it. But, it was designed like this on purpose. Can you imagine this meaning? There are 2 compartments inside. The first room is easy. But, it takes 21 moves to open the second room. I applied almost elements of traditional Himitsubako's main devices to my box.