Puzzle Box Sizes and Move Levels

Hakone puzzle boxes are usually labeled with two pieces of information: a size in sun and a number of moves or steps. Knowing what those numbers mean, and what they do not tell you, makes it much easier to choose a box.

Size: the sun system

A sun is a traditional Japanese unit of length. Izumiya, a Hakone maker of puzzle boxes, explains that 1 sun is about 30.3 millimeters, or about 1.22 inches, and that Hakone makers use the sun system to describe the approximate size of their boxes. Importantly, the sun measurement refers to length only. It does not describe the width or height, or the size of the compartment inside.

Values are calculated from 1 sun = 30.3 mm and rounded. Actual boxes vary, so check the listed dimensions when you buy. For example, the Hakone Karakuri Museum lists a 27-step, 4-sun box with outer dimensions of 115 x 81 x 52 mm and an interior of 71 x 64 x 28 mm.

Why the inside is so small

That example shows something that surprises many first-time buyers: the hidden compartment is much smaller than the box. The walls must hold the sliding panels, their channels and the stops that make the sequence work, and boxes with more moves need more room for the mechanism. If you want to hide a particular item, such as a ring, folded note or gift card, check the interior dimensions, not the sun size.

Moves or steps

The second number is the count of moves needed to open the box, sometimes written as steps. Izumiya states that most Japanese secret boxes range from 2 to 72 moves. Hakone Karakuri Museum listings include boxes of 7 steps, 21 steps and 27 steps, and a "27+1 steps" box. Beyond the usual range there are extreme examples: The Japan News reported that the Hakone Karakuri Museum displays a box that requires 1,536 steps.

How the moves feel varies by design, but the following general guide is useful:

• Few moves (single digits). A good introduction. The challenge is finding the first panel; once you do, the sequence is short. Suitable for children with an adult's help and for anyone new to puzzle boxes.
• Moderate counts (10 to the low 20s). A real puzzle. Expect panels to move back and forth in small steps. Notes help.
• High counts (27 and up). Patience boxes. The sequence is long and repetitive; the reward is persistence. Keep a written record so you can close the box again.

Move count is not the same as difficulty

A higher move count means a longer sequence, but not necessarily a harder idea. Some of the most puzzling boxes, especially modern karakuri boxes, open in just a few moves that are hard to discover because they use an unexpected trick. Conversely, a high-count traditional box can be mostly a matter of careful, repeated sliding once you understand which panels move.

Surface types

Boxes are also described by their surface. Hakone listings use names such as ko-yosegi (small-piece mosaic), kirichigai and other pattern names, or pictorial themes such as Mount Fuji. Izumiya describes zougan puzzle boxes as those with pictures on the top and bottom made from fitted pieces of colored wood. Some boxes are plain natural wood or lacquered. The patterns page explains the common mosaic designs.

Choosing a size and level

• As a desk object or first box: a small to medium box (around 2 to 4 sun) with a low move count.
• For hiding a gift: check interior dimensions; a 5-sun or larger box may be needed for anything more than a small item.
• For a puzzle enthusiast: a higher move count, or a karakuri box from a named maker.
• For a child: a low move count and sturdy size; supervise the first attempts so panels are not forced.

The buying guide covers how to tell genuine Hakone work from imitations, and puzzle boxes as gifts has ideas for presenting a box.

Reading a label: an example

Hakone Karakuri Museum listings show how the pieces of information fit together. One listing is titled "Japanese Puzzle box 27steps 4sun Koyosegi": 27 is the number of moves, 4 sun is the approximate length, and ko-yosegi is the surface style, small-piece mosaic. The listing then gives exact outer and interior dimensions. Another, "Japanese Puzzle Box 7steps Yui," is a 7-step box whose listed size is 209 x 98 x 57 mm, showing that a low move count does not mean a small box.

Sources

• Izumiya: Japanese Puzzle Box (Himitsu-Bako)
• Hakone Karakuri Museum: Japanese Puzzle Box 27 steps 4 sun Koyosegi
• Hakone Karakuri Museum: Japanese Puzzle Box 7 steps Yui
• The Japan News: Untangling secrets of Hakone’s puzzle boxes