Masyu (originally named Shiroshinju Kuroshinju, meaning 'White Pearls and Black Pearls') is a Nikoli loop-construction logic puzzle. Players must connect the centers of grid cells to draw a single continuous closed loop that passes through every circle according to specific geometric rules.

What is the rule for White Pearls (○) in Masyu?

The loop must travel straight through the white pearl's cell (entering and exiting on opposite sides without turning). Furthermore, the loop must make at least one 90-degree turn in the cell immediately preceding it or immediately following it (or both).

What is the rule for Black Pearls (●) in Masyu?

The loop must make a 90-degree turn inside the cell containing the black pearl. In addition, the loop must extend straight forward for at least one full cell length in both directions before it is allowed to turn.

Can the loop cross itself or branch?

No. The loop must be a single non-intersecting closed cycle without branches or dead ends.

Masyu (originally named Shiroshinju Kuroshinju, meaning 'White Pearls and Black Pearls') is a Nikoli loop-construction logic puzzle. Players must connect the centers of grid cells to draw a single continuous closed loop that passes through every circle according to specific geometric rules.

What is the rule for White Pearls (○) in Masyu?

The loop must travel straight through the white pearl's cell (entering and exiting on opposite sides without turning). Furthermore, the loop must make at least one 90-degree turn in the cell immediately preceding it or immediately following it (or both).

What is the rule for Black Pearls (●) in Masyu?

The loop must make a 90-degree turn inside the cell containing the black pearl. In addition, the loop must extend straight forward for at least one full cell length in both directions before it is allowed to turn.

Can the loop cross itself or branch?

No. The loop must be a single non-intersecting closed cycle without branches or dead ends.

Nikoli Classic • Pearl Loop

Masyu (Pearl Puzzle)

String together the necklace! Draw a single closed loop through every white and black pearl following Nikoli's turn and straight-line laws.

Warmup • 6×6

⏱ 0:00

Pearls Satisfied:0 / 6

Polishing Masyu pearl strand...

Masyu (Pearl Puzzle) Rules

Introduced in 1999 by the Japanese puzzle magazine Nikoli, Masyu requires deducing how a continuous cycle navigates constraints around two distinct pearl types:

⚪ White Pearl RulesMust pass straight through the pearl. Must make a 90° turn in at least one of the immediately neighboring cells (entry or exit).

⚫ Black Pearl RulesMust make a 90° turn inside the pearl. Must extend straight through the neighbor cells on both sides for at least 1 cell.

🔄 Single Closed LoopAll pearls must be united into one continuous closed circuit. Multiple loops or dead ends are strictly invalid.

❌ No IntersectionsLines cannot cross or touch each other. Visited cells must have exactly two edges connected to their center.

Core Theorems & Solving Strategies

Edge Black Pearls: A black pearl on the outer perimeter cannot turn towards the outside wall. Because both arms must extend straight for at least one cell, an edge black pearl must extend parallel to the border and point its other arm directly inward!
Adjacent Black Pearls: Two black pearls that are orthogonally adjacent must point their lines away from each other. They can never connect directly because both require extending straight for at least one full cell.
Consecutive White Pearls in a Line: When three or more white pearls lie in a straight row or column, the loop must travel perpendicular through all of them! Why? If it went parallel through all three, the middle white pearl could not turn in either neighboring cell without violating their straight-through rule.
Corner Pearls: A white pearl near a corner must exit parallel to the nearest wall, forcing an immediate turn at the boundary.

Explore More Nikoli Loop & Grid Puzzles

➰ Slitherlink (Loopy)🌉 Bridges (Hashi)💡 Light Up (Akari)⛺ Tents & Trees