Logic Masters Deutschland e.V.

1. Draw a line to make a single loop.
2. Lines pass through the centers of cells, horizontally, vertically, or turning. The loop never crosses itself, branches off, or goes through the same cell twice.
3. The numbers show how many black cells there are in the direction of the arrow.
4. The loop does not pass through the black cells or the cells with numbers, and black cells cannot touch horizontally or vertically.

For more detailed rule legends, please refer to: https://www.nikoli.co.jp/en/puzzles/yajilin.html

Author: 红葉 (MOMIJI), from China, this question comes from his personal blog.

PZV link

If you like this type of puzzle, you can go to this website to do more, https://www.janko.at/Raetsel/Yajilin/index.htm