Play Hitori Online

Shade cells to eliminate duplicate numbers in every row and column. Shaded cells can't touch, and all unshaded cells must stay connected. Pure logic — zero guesswork.

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Shaded Confirmed

Tap a cell to shade it — tap again to confirm or clear

What Is Hitori?

Hitori (ひとり, Japanese for "alone") is a logic puzzle published by Nikoli, the same company behind Sudoku. You start with an N×N grid already filled with numbers from 1 to N. Your task is to shade some cells so that three rules are satisfied:

  1. No duplicates: In each row and column, no number appears more than once among the unshaded cells.
  2. No touching: No two shaded cells may be horizontally or vertically adjacent.
  3. Stay connected: All unshaded cells must form a single connected group (you can reach any unshaded cell from any other by moving horizontally or vertically through unshaded cells).

The beauty of Hitori is that you're removing information rather than adding it. Every shading decision ripples across the board, affecting what can and can't be shaded elsewhere — making it a deeply satisfying logical chain reaction.

How to Play

  1. Choose a grid size and difficulty. 5×5 Easy is a gentle introduction. Larger grids with fewer givens are progressively harder.
  2. Tap a cell to shade it (dark). Tap again to mark it as confirmed/unshaded (green ring). Tap a third time to clear it back to default.
  3. Look for duplicates in rows and columns. Only one of each number can remain unshaded.
  4. Watch adjacency. If you shade a cell, neither its horizontal nor vertical neighbour can also be shaded.
  5. Keep cells connected. Every unshaded cell must be reachable from every other without crossing a shaded cell.
  6. Check your work with the ✅ button. Errors are highlighted in red.

Hitori Strategy Tips

1. Find Unique Numbers

If a number appears only once in both its row and its column, it can never be shaded — mark it as confirmed (green). These safe cells are your logical anchors.

2. Use the Adjacency Rule

If two identical numbers are adjacent (side by side), at most one can be shaded. This often means the other is forced to be unshaded. If three identical numbers appear in a row or column, the middle one is always unshaded (since shading it would force both neighbours to also be shaded — violating adjacency).

3. Watch the Connectivity

Shading a cell near an edge or corner can easily disconnect unshaded regions. Before you shade, mentally check: "Will all unshaded cells still be reachable?" If shading a cell would isolate even one unshaded cell, that move is invalid.

4. Between Two Shaded Cells

If two cells are shaded and there's a single unshaded cell between them (horizontally or vertically), that middle cell cannot be shaded — it would disconnect the unshaded region or violate adjacency. Mark it as confirmed.

5. Cascade From Certainties

Every confirmed cell eliminates its number from the "must shade" list for that row and column. Every shaded cell forces its neighbours to be unshaded. Work outward from what you know, and the cascading deductions will carry you through.

Hitori vs Sudoku

  • Starting point: Sudoku gives you a partially filled grid you must complete. Hitori gives you a fully filled grid you must selectively shade.
  • Action: In Sudoku you add numbers. In Hitori you remove (shade) them.
  • Constraints: Both require row/column uniqueness. Hitori adds adjacency and connectivity rules that require spatial reasoning.
  • Publisher: Both were popularised by the Japanese company Nikoli.

History of Hitori

Hitori was first published by Nikoli in the puzzle magazine Puzzle Communication Nikoli in 2001. It quickly gained popularity in Japan before spreading internationally through puzzle books, newspapers, and online platforms.

The puzzle's appeal lies in its unusual "subtractive" mechanic — instead of building up a solution, you're paring away to reveal it. This makes Hitori feel fundamentally different from most number puzzles, even though it shares the same Latin-square foundation as Sudoku and Futoshiki.

Hitori has been studied in computer science as an NP-complete problem, meaning that for arbitrarily large grids there is no known efficient algorithm to solve it. However, the human-solvable puzzles published in magazines (and generated here) are specifically designed to yield to logical deduction without brute-force search.

Frequently Asked Questions

Hitori (Japanese for "alone") is a logic puzzle on an N×N grid pre-filled with numbers. You shade some cells so that no number appears more than once in any row or column among unshaded cells, no two shaded cells are adjacent, and all unshaded cells form a single connected group.
In Sudoku you fill in missing numbers. In Hitori the grid is already full — you remove (shade) duplicates instead. Hitori also requires that shaded cells never touch and that all unshaded cells remain connected.
Start by marking cells that can't be shaded — numbers unique in both their row and column. Next, use the adjacency rule: if two identical numbers are adjacent, only one can be shaded. Finally, check connectivity after every move to avoid isolating unshaded cells.
Yes. Every puzzle on this site has exactly one solution and can be solved through pure logical deduction — no trial and error needed.
This version offers 5×5, 6×6, 8×8, and 10×10 grids. Smaller grids are great for beginners, while 8×8 and 10×10 provide a serious challenge. Each size also has Easy, Medium, and Hard difficulty levels.

More Puzzle & Strategy Games

If you enjoy Hitori, try these other free games on our site:

Futoshiki

Fill an N×N grid obeying inequality signs — Sudoku meets greater-than logic.

Kakuro

Mathematical crossword — fill runs of cells so they sum to the clue with no repeated digits.

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