How to Solve Hitori: Techniques That Actually Work

Updated June 2026

Hitori looks deceptively simple — a grid of numbers, and all you do is shade some of them. But the moment you try one, you discover it is a genuine logic puzzle with a small set of powerful deductions. Once those clicks into place, most boards stop feeling like guesswork and start solving themselves. This guide walks through the rules and then the handful of patterns that do almost all of the work.

The three rules, restated usefully

A Hitori board is a square grid filled with numbers. You shade (black out) some cells so that three conditions hold at once:

• No duplicates left. Among the cells you leave clear, no number may appear twice in the same row or the same column.
• No shaded cells touch. Two shaded cells may never sit directly beside each other — up, down, left, or right. (Touching at a diagonal corner is fine.)
• The clear cells stay connected. Every cell you leave white must be reachable from every other white cell by stepping through white cells only. You can never strand an island.

The trick to solving is that these three rules constantly feed each other. Shading a cell to kill a duplicate immediately forces its neighbours to stay white, which often kills another duplicate, and so on. Good solving is mostly about spotting where the rules collide and leave only one legal option.

Pattern 1: The triple — three in a line

When the same number appears three times in a single row or column with all three squeezed next to each other, you can solve it instantly. Only one of the three may stay white, so at least two must be shaded — but you are not allowed to shade two cells that touch. The only way out is to shade the two outer cells and keep the middle one white. The two ends are not adjacent to each other, so the no-touching rule is satisfied, and the duplicate is resolved. Whenever you see three identical neighbours in a line, the middle is white and the ends are black, every time.

Pattern 2: The pair with a gap — A · A

Suppose two identical numbers sit in the same line with exactly one different cell between them, like a 4, then a 7, then another 4. Exactly one of the two 4s has to be shaded. Now look at the 7 in the middle. If you shaded that 7, both of its neighbours — the two 4s — would be forced to stay white, because nothing can sit next to a shaded cell. But then both 4s are white in the same line, which is illegal. So the middle cell can never be shaded: the cell sandwiched between a matching pair is always white. This is one of the most common opening moves on a fresh board.

Pattern 3: Fence every shaded cell

This is less a pattern than a habit, and it is the engine that drives the whole solve. The instant you decide a cell is shaded, all four of its orthogonal neighbours must be white — there is no choice about it. Mark them as safe right away (in the game you can tap a cell twice to draw a circle on it as a reminder). Those newly confirmed white cells then act as anchors: any number that duplicates one of them, elsewhere in the same line, is now forced to be the shaded one. One shaded cell routinely cascades into a whole corner of fixed squares.

Pattern 4: Let connectivity break the tie

Sometimes pure duplicate-logic leaves you with two equally legal choices — either of two cells could be the shaded one. This is where the connectivity rule earns its keep. Before you shade a cell, glance at what it would cut off. If shading it would wall a white cell into a dead pocket, or sever the white region into two halves, then that cell cannot be shaded after all — and its partner must be. Corners and edges are the usual suspects: a cell in the corner with two shaded neighbours would be stranded, so at least one of those neighbours has to stay white.

Pattern 5: Read the board the way the game colours it

If you are solving on ujem, the board gives you live feedback that turns these rules into a checklist. A shaded cell turns red the moment it illegally touches another shaded cell, so you know instantly that one of them is wrong. A clear number glows orange while it still has a duplicate somewhere in its row or column, so the orange cells are literally your to-do list — the puzzle is finished exactly when the last orange disappears and nothing is red. Use that: shade the obvious forced cells first, fence them, and watch which oranges resolve on their own.

A sensible solving order

1. Scan every row and column for triples and pairs-with-a-gap, and mark those forced cells first.
2. Fence each shaded cell — circle its four neighbours as confirmed white.
3. Use the confirmed-white cells to force the shaded partner of any remaining duplicate.
4. When you stall, switch to connectivity: look for cells whose shading would strand a white square, and rule them out.
5. Only after all of that should you ever consider a tentative guess — and on a well-formed puzzle you almost never need to.

Every Hitori board on ujem has exactly one solution, which means you never have to gamble: there is always a forced move waiting somewhere if you look hard enough. The timed mode rewards the players who chase those forced chains quickly instead of stopping to reason about every cell.