Hitori

Hitori is solved by shading out cells on a number-filled square grid until, among the cells left white, no number repeats in any row or column — the numbers are never changed or moved, you only choose which cells to darken and which to leave showing.

What are the three rules of Hitori?

Two further rules keep the solution honest. First, no two shaded cells may touch edge-to-edge: shaded cells can meet at a diagonal corner, but never share a full side. Second, all the white cells must stay connected into a single group, so you can travel from any white cell to any other by stepping horizontally or vertically without ever crossing a shaded square. A shaded cell that walls off a pocket of white cells is illegal.

Why does every Hitori have exactly one solution?

These three constraints — no duplicates among the white cells, no touching shaded cells, one connected white region — pull against each other in a way that always leaves a single answer. Each of our boards is generated and checked to have exactly one solution reachable by pure logic, so you never have to guess: every shade can be justified, and so can every cell you choose to leave white. That is what makes Hitori a genuine deduction puzzle rather than a matter of trial and error.

The fastest way to solve Hitori is to lean on the two structural rules — no touching shaded cells, and one connected white region — because they constantly turn “maybe” cells into certainties.

What are the core Hitori solving tips?

Here are the core Hitori tips that do most of the work:

• A shaded cell forces its neighbours white. The moment you shade a cell, the cells directly above, below, left and right of it must stay white — two shaded cells can never touch. Mark those neighbours as confirmed white straight away.
• A number between two equal numbers stays white. If a value sits sandwiched between two copies of the same other number in a line — for example 3 4 3 — the middle cell (the 4) can never be shaded, because shading it would force one of the flanking 3s to shade too, and those two shaded cells would touch. The middle is safe.
• Three identical numbers in a line: shade the ends, keep the middle. When the same number appears three times consecutively in a row or column, the two outer copies must be shaded and the central one stays white. Shading the centre would leave a duplicate; leaving an outer pair white would too.
• Never break the white region. If shading a duplicate would cut off a white cell or seal a pocket from the rest of the board, that cell cannot be shaded — so its duplicate partner must be the one to go instead.
• Keep connectivity in mind near corners and edges. White cells in a corner only have two ways out; shading the wrong neighbour strands them. Use that to decide which of two equal numbers to remove.

What habits make Hitori easier?

Two good habits make all of this smoother. Mark your certain-white cells, not just your shaded ones — knowing a cell must stay white is just as powerful as knowing one is shaded, and it stops you double-shading by accident. And never guess: there is always a forced move somewhere, so when you feel stuck, re-scan the rows and columns for a duplicate whose fate is already decided by adjacency or connectivity.

Most Hitori deductions come down to a handful of recurring shapes — the pair, the triple, the flanked cell, the corner and the connectivity check — and learning to spot them solves boards far faster.

Which Hitori patterns should you memorise?

• The pair. Two of the same number in a line means at least one must be shaded — and because shaded cells can’t touch, two equal numbers sitting next to each other force exactly one to shade and the other to stay white.
• The triple. Three equal numbers in a row or column: the middle one stays white, the two ends are shaded. A reliable, instant solve wherever it appears.
• The flanked cell. Any cell caught between two copies of the same other value must stay white, because shading it would force a touching pair of shaded cells.
• The corner. A repeated number tucked in or near a corner is often pinned by connectivity — shade the wrong one and you isolate the corner cell, so the choice is forced.
• The connectivity check. Before committing a shade, glance at whether it would wall off any white cells. This “does the white stay joined up?” test is itself a pattern — and it frequently settles a fifty-fifty between two equal numbers.

A single row reading 2 5 5 5 1 shows Hitori in miniature: the three identical 5s trigger the triple pattern at once — shade the first and third 5, leave the middle 5 white. That instantly tells you something more — the cells directly above and below each shaded 5 must stay white, because nothing can touch a shaded cell. You have made three deductions from one pattern.

How does a flanked cell get resolved?

Now suppose a column contains the sequence 4 7 4. The 7 is flanked by two 4s. It must stay white: if you shaded it, you would still need to shade one of the 4s to clear that column’s duplicate, and a shaded 7 next to a shaded 4 would be two shaded cells touching — not allowed. So the 7 is confirmed white, and you turn your attention to which of the two 4s should be shaded instead.

How does connectivity force a shade?

Finally, picture a duplicate near the top-left corner. One copy could be shaded, but doing so would leave the corner cell with no white neighbour at all — it would be cut off from the rest of the board, breaking the connected-white rule. So that copy must stay white, and its partner elsewhere in the line is the one to shade. Three small steps, each one forced, and no guessing anywhere — that is Hitori in miniature.

Hitori comes in two sizes: the gentler 5×5 grid is quick to scan and ideal for learning the patterns, while the 6×6 grid has more rows and columns interacting, so duplicates chain together and the connectivity rule bites harder for a meatier solve.

Whichever size you choose, tap New for a fresh, uniquely solvable board at any time. There is also a shared Daily puzzle — the same grid for everyone that day — so you can compare your solve against friends. And if a board gets tangled, Reset clears your shading back to the starting numbers without changing the puzzle, so you can think it through again.

Hitori belongs to the family of shade-out puzzles — you solve it by deciding which cells to darken, never by writing anything in — which makes it a close cousin of Nurikabe and Nonogram in this collection. In Nurikabe you shade cells into a single connected “sea” while leaving numbered islands of exactly the right size — the mirror image of Hitori, where the white region must stay connected instead of the shaded one. And in Nonogram you shade cells according to numeric run-length clues to reveal a hidden picture. All three reward the same patient, cell-by-cell reasoning: read the constraints, find the forced cell, repeat. If you enjoy the quiet rhythm of shading by logic, any of them will feel like home.

A few words come up again and again in Hitori — shaded cell, white cell, duplicate, connectivity and adjacency — and here is what each one means.

• Shaded cell. A cell you have blacked out. Its number no longer counts towards the row or column. Shaded cells may meet at a corner but never share a full edge.
• White cell. A cell left unshaded, with its number still active. Every white cell must remain part of one connected group.
• Duplicate. A number that appears more than once among the white cells of a single row or column. Clearing every duplicate — by shading the right copies — is the heart of the puzzle.
• Connectivity. The requirement that all white cells form a single joined-up region, reachable from one another by horizontal and vertical steps. A shade that isolates any white cell is illegal.
• Adjacency. Cells that touch edge-to-edge — above, below, left or right (not diagonally). The “no two shaded cells adjacent” rule is defined by this.

The most common Hitori mistakes are shading two cells that touch, accidentally sealing off the white region, shading both copies of a number, ignoring confirmed-white cells, and guessing under pressure.

• Shading two cells that touch. The most frequent slip — always check a new shade against its four neighbours before moving on. On this site such a cell turns red to warn you.
• Forgetting the white region. It is easy to clear duplicates correctly yet accidentally seal off a pocket of white cells. Keep glancing at whether everything white is still joined up.
• Shading too eagerly. A number appearing twice does not mean both copies are wrong — usually only one is shaded and the other stays white. Decide which, don’t shade both.
• Ignoring confirmed-white cells. If you only track shaded cells, you lose half the information. Mark cells that must stay white too; they often force the next shade.
• Guessing under pressure. Every board has a logical next step. Resorting to a guess usually leads to a contradiction later — re-scan instead.

Hitori is a wonderfully focused little workout: because there is no arithmetic — the numbers are just symbols to compare — it exercises pure pattern recognition, spatial reasoning and careful, step-by-step logic. Spotting a triple, tracing whether the white cells stay connected, weighing which of two duplicates to remove: each move sharpens attention and working memory in a calm, low-stakes way.

It is also deeply fair. With exactly one logical solution on every board, progress always feels earned — there is no luck and no dead end you could not have avoided. A 5×5 makes a perfect short break; a 6×6 is a satisfying sit-down challenge. And if you like the way Hitori turns a few rules into one exact picture, the same pleasure waits in Nurikabe and the Nonogram shading puzzles here.

Hitori is a Japanese pencil puzzle popularised by the publisher Nikoli, the same house behind many of the grid logic puzzles known worldwide. Like its stablemates, it spread from puzzle magazines into newspapers, books and apps, prized for needing nothing but a grid of numbers and clear thinking.

The name carries a neat joke about the goal. It comes from the Japanese phrase “hitori ni shite kure”, which means roughly “leave me alone” — a nod to the aim of leaving each number alone, unrepeated, in its row and column. For that reason it is sometimes rendered in English simply as “Hitori”. It is a fitting label for a puzzle whose whole purpose is to give every surviving number its own private space.