Renju (Japanese: 連珠) is the professional variant of Gomoku. It was named Renju by Japanese journalist Ruikou Kuroiwa (黒岩涙香) on December 6, 1899 in a Japanese newspaper Yorozu chouhou (萬朝報). The name "Renju" comes from the Japanese language, and means connected pearls in Japanese literally. The game is played with black and white stones on a 15×15 gridded Go board.
The rule of Renju weakens the advantages for the first player (Black) in Gomoku by adding special restrictions for Black.