Among our crosswords and other puzzles, Atlas Obscura features logic challenges from Puzzle Communication Nikoli, a cult-favorite puzzle publication from Japan. A PDF of the puzzle, as well as the solution, can be downloaded below.

Fans of the kind of grid-based logic puzzles that are the calling card of Puzzle Communication Nikoli, Japan’s highly influential puzzle magazine, will certainly see elements repeated. There are puzzles that ask you to draw looping lines, cells with numbers or circles in them, arrows pointing this way and that. Adding a fresh element is like giving Nikoli’s puzzle maker–readers a new toy to play around with.

Take the puzzle called Yajisan-Kazusan, created in the mid-1990s. It had something that hadn’t been seen in a Nikoli puzzle before, a cell that contains both a number and an arrow. But it was tricky, and involved some numbers that were fake and had to be blacked out. While it appealed to some of the magazine’s more intense and clever puzzle solvers—“maniacs,” jokes Nikoli president and puzzle creator Yoshinao Anpuku—it never caught on with the wider readership. But the readers who actively create new puzzles for Nikoli, saw something in it they could use.

In 1999, the puzzle creator named Tempo came up with Yajilin, a puzzle that remixed the number-arrow cell with Nikoli’s distinctive continuous loops. The result was a puzzle that can be reasoned out quickly, complex but with a difficulty that scales, which made it very popular. Some consider it superior to other popular loop puzzles, such as Slitherlink and Masyu.

The goal of Yajilin is to both shade in black cells and draw a single, continuous loop through the remaining white cells, so that every cell of the grid is filled. The cells containing numbers and arrows are the only signposts on an otherwise featureless grid.

The numbered cells show how many black cells the solver must draw in the direction of the arrow, while drawing a continuous loop through all the cells that are neither black nor numbered. It’s a great entry to the world of Nikoli’s looping logic.