Japanese secret box made entirely by hand.
The lid seems to move, but you won't be able to open it in the usual ways... you'll need a single winning move!
CHALLENGE: open the secret box
Difficulty: 3/6 HARD*. Average solution time: 10 minutes - 1 week
Dimensions: 7.8 × 9 × 6.6 cm / 3 x 3.5 x 2.6 inches
Internal space: 4.6 × 5.5 × 2.1cm / 1.8 x 2.1 x 0.8 inches
Made with teak wood and camphor tree
Made manually on Lake Ashi in Japan, in a village of artisans who have been engaged in wood inlay work for approximately 300 years.

*difficulty level and solution time are subjective. Much will depend on the skills of the individual player.

Yosegi inlay work
It is said that the yosegi inlay works, typical of Hakone which is on Lake Ashi, were born thanks to the work of Nihei Ishikawa, during the last period of the Edo era (1603-1868).
Hakone's inlay works, enhancing the infinite variations in the natural color of the wood and the traces of its grain, represent one of the most sophisticated woodworking techniques, a manifestation of an art that expresses the perfection of geometric motifs through refined skill manual handed down for generations. Objects such as boxes or drawers are made through a particular filing process using a special plane, and the refined tablets depicting particular motifs are shaped to form trays or bowls.