What is Hitori?
Hitori is a logic puzzle played on a grid that is already full of numbers. Some of them repeat, and your task is to shade the extra copies away. There are two catches: shaded cells can never touch, and the white cells must always stay joined.
It is a quick, clever puzzle for fans of sudoku. Play Hitori online free here.
Where Hitori comes from
Hitori, which means “alone” in Japanese, was published by Nikoli. You start with a full grid of numbers and remove the duplicates by shading cells, until no number appears twice in any row or column.
How to play here
With a mouse, left-click a cell to shade it and right-click to circle it, which marks a cell that must stay white. On a phone, tap to shade and use Mark mode (the flag button next to Undo) to circle. Circling is optional but makes long solves much easier.
The three rules
- No number may appear twice in a row or column among the unshaded cells.
- Shaded cells may never touch each other side by side.
- All unshaded cells must stay connected as one group.
A step-by-step way to solve
- Look for triples. In three identical numbers in a row, like 5 5 5, the middle one must stay white and both ends must be shaded.
- Between a pair, the middle is white. In a pattern like 4 x 4, the cell between the two 4s must stay white, because one of the 4s will be shaded and shaded cells cannot touch.
- Circle around every shaded cell. Its four neighbors must all be white.
- Protect the connections. If shading a cell would cut off a white cell or a group from the rest, that cell must stay white.
- Finish the duplicates. Once one copy of a number in a line is circled, all other copies in that line are shaded.
Why play Hitori?
Hitori works in reverse: the answer is already on the board and you remove what does not belong. That makes it a great change from placing puzzles. Try Akari or Nonograms next for more shading logic.
How to play Hitori
- Shade cells so that no number appears twice in any row or column.
- Shaded cells may not touch each other side by side. Diagonal contact is fine.
- All unshaded cells must stay connected in one group.
Hitori tips
Look for triples
In the pattern 3 3 3, the middle 3 stays white and both outer 3s are shaded, since two touching shaded cells are not allowed.
Circle cells that must stay white
Every cell next to a shaded cell must be white. Mark them, then shade any duplicates of those numbers in the same row and column.
Protect connections
If shading a cell would cut the white area in two, that cell must stay white.
Frequently asked questions
What does Hitori mean?
Hitori is Japanese for alone, referring to leaving each number alone in its row and column.
Can shaded cells touch at the corners?
Yes. Shaded cells may only touch diagonally, never along an edge.
Is there one solution to each Hitori?
Yes, every puzzle here has a unique solution reached by logic.
