Kurodoko, a Daily Puzzle in Black and White

Field notes

The 5×5 grid uses three cell states—white, black, and clear—and provides Check and Hint controls as players work through the deduction. Numbered cells count visible white squares along four straight directions, while black cells cannot share an edge and the remaining white cells must form one connected region. The page also identifies Kurodoko with the Japanese names 黒どこ and 黒マス, attributes the puzzle to Nikoli, and links to an archive.