This puzzle is part of the Monthly Topic Challenge #14: Think inside the (very small) box!.
Rules of regional Yajilin:
- Shade some cells in the grid. Two shaded cells cannot share an edge, but can touch at a corner.
- Draw a single loop, going horizontally and vertically through centres of cells, which visits every unshaded cell and none of the shaded cells. The loop cannot cross itself or branch out.
- A number in the top-left corner of a cage marked with dotted lines indicates how many shaded cells are inside the cage.