The Origin of Kai-Awase(Matching shells)
Kai-awase was born in the Heian period(794-1185 A.D.) as a past time of drawing pictures and letters in shells. Soon, people started to separate the shell into two and played by trying to match them. Noble people also enjoyed writing Waka(syllable Japanese poems) and drawing beautiful pictures along with them. Their favorite motif was Genji-monogatari('the tale of Genji',known as the oldest romance novel in the world).
As the time passed by, Kai-awase became more sophisticated that even the buckets to put the shells in played important rolls in weddings for families of feudal lords. The buckets were given to the brides as special gifts. Now a days, this ceremony is called 'the ceremony of Kai-awase' and it still remains in Shinto-style weddings.
The best shells to use in these ceremonies are said to be the 3 inch clams taken from Kiso-river in Mie prefecture. That is because of their beautiful patterns and thickness, and also, they are a size that perfectly fits in women's hands.
We at MIkawa-Kobo also use clams from this place and paint by hand.
One of the reasons to give Kai-awase to brides and new-born girls is that two clams never match one another. This suggests some meanings in charms like you never separate once you get married, or you never chose the wrong partner.
These superstitions made wealthy families of feudal lords make vast numbers of gorgeously decorated Kai-Awases. These are shaped by powdered calcium carbonate and covered in gold foils, then painted with the pictures that express the story of Genji-monogatari. The painting style used in these pictures is usually Tosa-school.