The story
Japanese, from a misreading of 真珠 (shinju, “pearl”) (the game was originally called 真珠の首飾り (shinju no kubikazari, “Pearl Necklace”)).
Etymology from Wiktionary, CC BY-SA 4.0.
masyu
Today it means: A logic puzzle in which the player must link circles on a rectangular grid so as to form a continuous loop that passes once through every circle. Full definition →