Normal sudoku rules apply. Colors used in this puzzle are Black and Red. For best results, remove all unshaded marking you've done once complete. Japanese Sums rules: the squares outside the grid indicate the order of the contiguous runs of cells found in that row or column that must be shaded the color of the clue. The number inside the clue gives the sum of the cells in the run. There must be at least one unshaded cell between runs of the same color, but there is no need between runs of differing colors. All runs are given.