Gamaguchi means in Japanese "frog mouth". It designates an accessory that opens and closes with a metal clasp. They are very popular in Japan often accompanying a traditional outfit. This type of clasp from Europe was introduced in the Meiji era (1868-1912).
Very practical to store your money in a clap, they remind us of our childhood. Depending on your preference, it is possible to adjust the opening system of this object towards more flexibility or firmness.