Normal sudoku and Nurimisaki rules apply. In addition, orthogonally adjacent cells along the Nurimisaki path (unshaded cells) have a difference of at least 5. Nurimisaki Rules are as follows: Shade some cells so that the remaining unshaded cells form one orthogonally connected area. No 2x2 region may be entirely shaded or unshaded. Circles mark every instance of a cell which is unshaded and orthogonally adjacent to exactly one other unshaded cell (i.e. the circles are the only ‘endpoints’ of the unshaded area). The digit in a circle indicates how many cells are in the straight line of unshaded cells coming out of the cell with the circle, including itself.