Hitori Puzzle

Printable Hitori Puzzles: Shade the Duplicates

Hitori is a Japanese shading puzzle that flips Sudoku on its head. Instead of placing digits, you shade cells to remove them, until no row or column contains any repeated number. The puzzle is subtle, tactile and hugely satisfying once you get the hang of the rules.

This generator produces print-ready Hitori puzzles in A4 or US Letter PDF format, with two puzzles per page on a friendly 6x6 board (7x7 and 8x8 grids are also supported). A separate solution page is optional. Hitori is a great quiet-time activity, travel puzzle, puzzle-club handout and brain-training routine for children and adults alike.

Pattern recognition is the heart of Hitori. You learn to scan rows and columns for duplicates, then reason about which of the duplicates to shade given the constraints around them. It is deductive reasoning in the purest sense.

How the Hitori rules work

Start with a grid where every cell contains a digit. Your job is to shade some cells according to three rules.

• No row or column may contain the same unshaded digit more than once.
• No two shaded cells may be orthogonally adjacent (they may touch diagonally).
• All unshaded cells must remain connected into a single orthogonal region.

The three rules work against each other in interesting ways. Shading too eagerly can leave the unshaded region broken in two, which is illegal. Shading too cautiously leaves duplicates behind.

Who Hitori is for

Beginners

Hitori is unusual because you do not need any arithmetic. The rules are geometric, which makes it accessible for children who are still learning numbers.

Puzzle enthusiasts

Seasoned solvers enjoy Hitori for its elegant dual constraints. Ruling out a shading because it would break connectivity is uniquely satisfying.

Classroom teachers

Hitori is a calm visual activity that builds reasoning skills without arithmetic load. Two puzzles per page sits nicely in a puzzle-club handout.

Parents

Print a page for a long car trip or a quiet evening. Children love crossing out cells with a pencil because the tactile feedback is immediate.

What you can customise

• Grid size: 6, 7 or 8 cells per side.
• Puzzle count: two per page for a clear layout.
• Include solutions: toggle the second page of fully shaded grids.
• Seed: reproduce the same set on demand.
• Paper size: A4 or US Letter PDF output.

Worked example

Imagine three cells in a row reading 3 3 3. At least two of the three must be shaded (to leave only one unshaded 3), but you cannot shade two adjacent cells. The only legal pattern is to shade the outer two and keep the middle unshaded. That is a classic Hitori deduction called the “triple trick”.

Another common pattern is a pair like 5 5 where a 5 already sits elsewhere in the same row. Both members of the pair must become shaded, but they are adjacent, so the puzzle is impossible as stated. In practice this kind of contradiction tells you a nearby cell must be shaded first to rule out one member.

How to use the tool

1. Choose a grid size of 6, 7 or 8.
2. Decide whether to include the solutions page.
3. Optionally set a seed for a repeatable set.
4. Select A4 or US Letter paper.
5. Click Generate and preview the puzzles.
6. Download the PDF and print at 100% scale.

Methodology

The generator builds a grid by starting from a valid shading pattern (respecting the three rules) and then filling the grid with digits so the pattern is consistent. In v1 the engine uses a greedy approach, so some puzzles may admit more than one valid shading. The printed solution is one valid answer. Future versions will tighten uniqueness.

Tips for solving

• Hunt for triples. A row of three identical digits has a forced shading pattern.
• When a pair is flanked on both sides, both outer cells are often forced unshaded to protect connectivity.
• Mark cells that must stay unshaded with a small circle. That keeps your deductions visible without committing to ink.
• Check connectivity often. A puzzle that otherwise looks solved can still fail the connected-region rule.

Designed for A4 and US Letter printing

The PDF prints cleanly on both paper sizes. Two puzzles per page with a 6x6, 7x7 or 8x8 grid keeps every digit readable and leaves room to shade cells firmly with a pencil.

Why Hitori is a satisfying form of brain training

Sudoku asks you to fill cells, Hitori asks you to erase them. That inversion changes how you think. Instead of chasing what each cell should be, you chase what each cell must not be. That switch of perspective is why Hitori appeals to solvers who have grown tired of filling-in puzzles, and why it is often described as a more visual or spatial puzzle than Sudoku.

The connectivity rule adds another layer. At any moment you might identify a shading pattern that satisfies the row and column rules perfectly, only to realise it cuts the unshaded region into two disconnected parts. That kind of global constraint forces solvers to zoom out regularly, which is a useful habit for any kind of deductive reasoning.

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