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Draw a single, non-intersecting loop that passes orthogonally through all circled cells. The loop must go straight through the cells with white circles, with a turn in at least one of the cells immediately before or after each white circle. The loop must make a turn in all the black circles but must go straight in both cells immediately before and after each black circle.

(Rules and example from PGP IB)

History of the puzzle[edit]

First appeared on Nikoli volume 90 (2000) under the name of "白真珠黒真珠" ("White pearls, black pearls"). Invented by アセトニトリル ("Acetonitril"). Renamed to "ましゅ" ("Masyu") in volume 103 (2003).

This puzzle was suggested as a modified version of "真珠の首飾り" ("Pearl earring") by 矢野龍王 ("Yano Ryuoh"), first appeared in 1999, where only white circles were present.


See List of Masyu variants.

Appearances in the past WPCs[edit]

Listed here are appearances of classic to almost-classic Masyus. For variants, see list of Masyu variants#Appearances in the past WPCs.