Normal sudoku rules apply. Shade some cells such that all shaded cells are orthogonally connected, all unshaded cells are orthogonally connected, and no 2x2 area is fully shaded or fully unshaded. A digit in a cell with an arrow counts the total number of shaded cells seen in the direction of the arrow (not counting the cell itself). For every 2x2 area in the puzzle, no two shaded cells can be from the same modulo 3 set. In other words, in any given 2x2 area, there can only be one shaded cell with a digit from [147], one from [258], and one from [369].