THREE RULES, AND YOU'RE SHADING — NOT WRITING
A Hitori starts completely full of numbers. You never add any — you only shade squares black to take them out of play. The finished grid has to obey three things:
- No number repeats in any row or column — counting only the white (unshaded) squares. If a number shows up twice in a line, one of them has to go black.
- No two black squares may touch — not side by side, not stacked. They can sit diagonally, but never edge to edge.
- The white squares all stay connected — one single island, so you could walk between any two white squares without crossing a black one.
That second rule is the secret weapon. "Two blacks can't touch" sounds like a restriction, but it constantly tells you which square must stay white — which often tells you exactly which one to shade instead.
LET'S ACTUALLY SOLVE ONE — STEP BY STEP
Here's a real 5×5 Hitori, every square full of numbers. Look at the top row: it opens 4, 4, 4 — three of the same number in a line. That's the gift. We'll start right there.
The starting grid — full of numbers. The top-left three squares are all 4s.
Step 1 — three in a row: shade the ends, keep the middle.
A row can only keep one 4, so two of these three have to go black. Which two? Try shading the middle one — then a neighbouring 4 would have to stay white, but its only partner is also a 4 that needs shading, and you'd end up with two blacks touching. That's illegal. The only arrangement that works: shade both ends, leave the middle white. Three of a kind in a line is the most generous thing on a Hitori board — always hunt for one first.
Step 2 — "can't touch" decides a tie.
Drop to the second row — it has two 2s, so one must go black. The left one sits directly under a black square we just made. Shade it and the two blacks would touch — not allowed. So that 2 is forced to stay white, which means the other 2, off on the right, is the one that gets shaded. The rule you couldn't use a minute ago just picked the answer for you.
Step 3 — a white square you already locked in does the same job.
Now look down the second column: two 4s. But the top one is the white middle of our triple — we already decided it's staying. A column keeps only one 4, so the lower 4 must be shaded. Every square you settle ripples outward and settles others — that's the whole rhythm of Hitori.
Four squares shaded, and the rest fall out the same way: hunt the repeats, let "no touching" and "stay connected" break the ties. Here's the finished grid:
Done. No black squares touch, the white ones are all joined up, and no number repeats. 👻
THE TWO CHECKS THAT KEEP YOU HONEST
When the obvious triples and pairs run out, these two rules keep handing you moves — still no guessing.
1. The moment you shade a square, its neighbours go white.
Because two blacks can't touch, every square next to a black one is instantly safe — it's staying white. Mark those in your head. Often one of them is a duplicate whose partner is now the square that has to be shaded. A single black square can set off a little chain of these.
2. Never strand a white square.
Before you commit to shading a square, glance at whether it would cut a white square (or a clump of them) off from the rest. If shading here would trap some white squares in a corner with black on all sides, this square can't be the one — its duplicate is. The "all white stays connected" rule quietly rules out a lot of tempting-looking shades.
So the loop is: shade the forced duplicates (triples first), turn each new black into a ring of guaranteed-white neighbours, and refuse any shade that would split the white region. Every black square has a reason — Hitori never needs a guess.
THAT'S IT — GO DO ONE
Find the repeats, black out the ones that have to go, and let "no touching" and "stay connected" settle every tie. The first time a single black square cascades into five more, it feels great. No words, no maths, no ads in the middle of your puzzle — just you, a grid of numbers, and a ghost quietly pleased when the last square clicks.