Wikipedia
Shūgi-bukuro
A is a special envelope in which money is given as a gift at weddings in Japan.
It is very common in Japan to give a gift of money at weddings. The giver inserts the money into a shūgi-bukuro on which they have written their name. The shūgi-bukuro is handed to the receptionist of the reception party. Shūgi-bukuro are sold at supermarkets and stationery stores.