Hiroshi Fujino and the Puzzles That Must Not Fall

Most packing puzzles ask one question: do the pieces fit? Hiroshi Fujino asks a second one, and it is the question that ruins your first dozen solutions. Will they stay in when you turn the box over?

That is the whole idea behind the Ochinai series. Ochinai is Japanese for "will not fall", and it is a specification rather than a name.

These are also the first puzzles Hiroshi Fujino has released anywhere. The Ochinai series debuted on Greg Puzzles, worldwide, and the story of how that happened is further down.

The Rule That Makes an Ochinai Puzzle Different

A normal packing puzzle is finished when everything is inside and nothing sticks out. Fujino's boxes are not finished there. They have a large opening cut into them, and the puzzle is only solved when you invert the box over your hand and nothing drops out.

Those two conditions pull in opposite directions. Packing wants the pieces wherever they happen to fit. Not-falling wants them braced against each other across a gap with nothing underneath. A great many arrangements satisfy the first rule and fail the second, which is why the puzzle feels solved repeatedly before it actually is.

The Corner Is the Puzzle

Look closely at the boxes and you find the detail that does the damage. The opening is not a window in one face. It is cut across a corner, so the hole wraps around an edge and takes part of two faces with it.

A flat hole in one wall would be comparatively kind - pieces could still rest on the floor and lean on the walls. A corner opening removes the floor and a wall at the same place. Any piece sitting over that corner has nothing beneath it and nothing beside it, so it has to be held by the pieces around it or it leaves.

So the real work is not packing. It is deciding which piece gets to occupy the corner, and what holds it there.

Two Boxes, Not One Puzzle

Each Ochinai set ships as two boxes with differently shaped openings, and they are genuinely separate problems. The same pieces, the same cavity, a different hole - and the solution that worked in the first box is of no use in the second.

It is an efficient piece of design. The cost of a second puzzle is one more printed box, and the difficulty does not repeat.

Ochinai Soma

Ochinai Soma uses the seven Soma cube pieces, which is a deliberately loaded choice. The Soma is famous for having 240 solutions - it is the standard example of a puzzle with so many answers that it is hard to fail.

Fujino takes that abundance away. Most of those 240 arrangements will not survive being turned upside down over a corner hole, so a puzzle known for generosity becomes a puzzle about a narrow set of survivors. If you already own a Soma, this is the version that makes it difficult again.

Ochinai Tromino

Ochinai Tromino swaps in nine tromino pieces - the small three-cube shapes - and the change in character is sharper than the piece count suggests.

Trominoes are short. A long piece can span a gap and rest its ends on solid floor either side, which is the easy way to survive the inversion. Short pieces cannot span anything, so every one of them has to be held by a neighbour, and the whole arrangement has to lock together rather than merely sit there.

Both Boxes Hold Twenty-Seven Cubes

Worth noticing, because it tells you what kind of puzzle you are holding. The seven Soma pieces are twenty-seven unit cubes between them. Nine trominoes, at three cubes each, are also twenty-seven.

Both sets fill the same three-by-three-by-three space exactly, with nothing spare. There is no slack anywhere in either puzzle - every cube of the box has to be occupied, and the inversion still has to survive. A single wasted gap and the packing has already failed before gravity gets a say.

How to Solve an Ochinai Puzzle

No two solutions are alike, so this is method rather than answer:

Start at the hole, not at the corner furthest from it. The instinct is to fill the solid part first and deal with the opening last, which guarantees that whatever is left over is what ends up over the gap. Decide early what sits at the opening.

Ask what is underneath each piece as you place it. Over solid floor, anything works. Over the opening, the piece needs a neighbour it can press against, and that neighbour needs to be held by something itself.

Test early. Do not pack the whole box and then turn it over. Fill it part way, invert it, and find out which pieces are load-bearing while you can still see what is happening.

Expect to be wrong about being finished. The arrangement that fits perfectly and empties itself onto the table is the normal experience, several times over, and it is the puzzle working as intended.

How These Came to Be Here

This part I am still slightly delighted by. Hiroshi Fujino was a customer first. He bought puzzles from us, won one of our giveaways, and we started talking the way you do with someone who clearly loves the same things you do.

Then one day he came to me with a puzzle he had designed himself. I looked at it, and I liked it immediately - not politely, genuinely. The idea was better than most things I get sent.

So Hiro-san's puzzles launched here, and nowhere before. The Ochinai series had its first release anywhere in the world on Greg Puzzles, which is not a sentence I have been able to write often, and I am still quite excited about it.

It also tells you something about the design. These were not pitched by a studio with a catalogue to fill. They came from a person who solves puzzles for pleasure, noticed a constraint nobody was using, and built two boxes around it.

Why This Design Is Unusual

Puzzle designers normally add difficulty by adding constraint to the pieces - stranger shapes, tighter tolerances, an awkward box. Fujino leaves the pieces alone and adds a rule that is enforced by gravity.

That is a rare move, and it has a quality worth naming: the puzzle checks your answer for you. There is no solution sheet to consult and no ambiguity about whether you have finished. You turn the box over. The pieces stay, or they are on the floor.

It also means the puzzle cannot be fudged. With an ordinary packing puzzle you can sometimes jam a piece and declare victory. Here the test is physical and it is not interested in your opinion.

Who These Are For

Someone who has solved a lot of packing puzzles and wants the category to be hard again. The mechanical puzzles range has plenty that are difficult because the fit is tight; these are difficult because a correct fit is not enough.

They are also a good fit for anyone who likes spatial reasoning puzzles, because the thing you have to picture is not just the shape of the gap but which surfaces are load-bearing.

A Note on the Name

Fujino's puzzles reach most English-speaking solvers through their Japanese titles, and we have left them that way. Ochinai carries the rule in the word, and translating it to something like "No Drop" would lose that.

His name is written 藤野　浩. We print it as he does, because a designer's name in his own script is his, not a detail to approximate.

Frequently Asked Questions

What does Ochinai mean?

It is Japanese for "will not fall". In these puzzles it is the actual win condition: the pieces have to stay in the box when it is turned over.

How is Ochinai Soma different from a normal Soma cube?

Same seven pieces, one extra rule. A standard Soma cube has 240 solutions; here the box has a corner opening and most of those arrangements fall out when inverted, so only a small number actually count.

Why are there two boxes in the set?

Because they are two puzzles. The openings are cut differently, so a solution found for one box does not transfer to the other.

Which is harder, Ochinai Soma or Ochinai Tromino?

Tromino tends to be the tougher of the two. Its pieces are short, so none of them can bridge the opening and rest on solid floor at both ends - every piece has to be supported by another piece.

Do you need to know the Soma cube first?

No, though it helps you appreciate the joke. Knowing the Soma as the puzzle with 240 answers makes it funnier when almost none of them survive the box being turned over.