Masyu
Masyu is a loop-drawing logic puzzle invented by the Japanese puzzle author known under the alias Acetonitril. It first appeared in Puzzle Communication Nikoli, volume 90, in 2000, under the name 白真珠黒真珠 (Shiroshinju Kuroshinju, “White Pearls and Black Pearls”). The puzzle was officially renamed ましゅ (Masyu) in volume 103 (2003).
The concept of Masyu evolved from an earlier puzzle called 真珠の首飾り (Shinju no Kubikazari, “Pearl Necklace”), proposed by Yano Ryuoh and first published in 1999. That earlier version contained only white circles. Black circles were introduced later, significantly enriching the logic and leading to the modern form of Masyu.
In the puzzle, a single closed loop must be drawn through the grid. White and black circles impose different constraints on how the loop must pass through or turn at those cells, creating a balance between local conditions and global loop structure.
The name Masyu itself has no clear literal meaning. It is widely believed to originate from a misreading of the kanji 真珠 (shinju, “pearls”) by Nikoli’s editor-in-chief. Despite its accidental origin, the name was officially adopted and has since become standard worldwide.
Masyu is also known under alternative names such as Mashu, Mashi, Pearls, and White Pearls and Black Pearls, and it has inspired many variants over the years.
The concept of Masyu evolved from an earlier puzzle called 真珠の首飾り (Shinju no Kubikazari, “Pearl Necklace”), proposed by Yano Ryuoh and first published in 1999. That earlier version contained only white circles. Black circles were introduced later, significantly enriching the logic and leading to the modern form of Masyu.
In the puzzle, a single closed loop must be drawn through the grid. White and black circles impose different constraints on how the loop must pass through or turn at those cells, creating a balance between local conditions and global loop structure.
The name Masyu itself has no clear literal meaning. It is widely believed to originate from a misreading of the kanji 真珠 (shinju, “pearls”) by Nikoli’s editor-in-chief. Despite its accidental origin, the name was officially adopted and has since become standard worldwide.
Masyu is also known under alternative names such as Mashu, Mashi, Pearls, and White Pearls and Black Pearls, and it has inspired many variants over the years.
Rules
Draw a single closed loop which runs horizontally or vertically between the centers of the cells. The loop cannot intersect or touch itself. The loop must visit all cells with circles. In a cell with a black circle the loop must turn by 90° and must travel straight through the previous and next cell. In a cell with a white circle the loop must travel straight through and must turn by 90° on the previous or the next cell.
Click to see the answer.