1. Divide the grid into L shaped blocks – one block wide. All blocks must be L shaped.
  2. Cells with open circles form the knee (bend) in a block.
  3. The number in an open circle shows the number of cells in its block.Open circles without numbers may have any number of cells.
  4. Cells with arrows form one end of its block, the arrow points towards the knee of this block.
  5. The number of marks in a block (arrows or open circles) may be 0, 1, 2, or 3.
    *Sashigane is the Japanese for a carpenter’s square.

List of puzzles