Normal Sudoku rules apply. Place the digits 1–9 in every row, every column and every 3×3 box.

The arrows show all places where the parity of the next four digits in the indicated direction spell out the cell’s digit in binary. Even digits signify a binary ‘0’ and odd digits a binary ‘1’.

For example: if a cell with a right-pointing arrow contains the digit 5, then the next four digits to the right could be 8, 1, 4, 3. These are even, odd, even, odd, which translates to 0101, which is indeed binary for 5.

Note that left-pointing arrows have the binary number written backwards (example: 7 2 3 6◀5) and up-pointing arrows have it upside-down.

The negative constraint applies. If a cell contains a 6, all directions with no arrow must not spell out 0110 in binary parity.