Kai-awase

Kai-awase is a game that started in the Heian period. The original game, using shells, was played by Heian aristocrats who would compose poems about the shape, size, and color of clams, and then compete against each other to see how well they wrote songs.^[2] It became popular among aristocrats in the late 12th century.^[3] During the late 12th century, "Kaiōi" was a game in which multiple pieces of clam shells were mixed up, separated from the left and right sides, and players would find a pair among them. "Kaiōi" began as a game for women from the late Heian period to the Kamakura period, but by the late 13th century, it came to be called "Kai-awase".^[3][4] In the late 13th century, shells became increasingly elaborate and beautiful for the purpose of play and comparison. Gold and silver were even added to them, making them gradually become decorative items.^[3] During the Sengoku period to the Edo period, the shells of kai-awase were also used as decorations with blessings in upper-class weddings.^[4] In the modern context, the meaning of the word "Kai-awase" has evolved to refer more to shellfish matching, which is a game of matching pairs of objects, rather than a competition of reciting songs.^[4]