Karakuri Small Box: Block R

A very small puzzle box with a grid pattern in the vertical and horizontal directions.  There is no obvious mechanism so where will it open?  Quality workmanship makes the secret very hard to find!  Once you know the trick, it is very simple.

This puzzle box is so small that you can take it along with you and show it to your friends to see if they can solve it.

Note; Small block-C and Small block-R open in a similar way.
C is a cube, and R is a rectangular cuboid.

Craftsman : Osamu Kasho
Material : walnut, magnolia

Solution is included.

"Karakuri Creation Group doesn’t have a history of making devilishly difficult puzzles – they have a reputation of being genious craftsmen.  And their works are of supreme quality." - The Puzzle Wanderer