Can shaded cells touch diagonally?
Yes, only orthogonal touching is forbidden.
What happens if I shade a corner?
Corner cells have fewer neighbors, so shading them is more likely to cause connectivity issues.
Can a row have no shaded cells?
Yes, if all numbers in that row are already unique.
Is Hitori about math?
No, the numbers are labels. The puzzle is about elimination and connectivity.
How do I know when I am stuck?
If every remaining duplicate has at least one safe shading option, look for connectivity traps.
