I think this is my favourite postcard. The title of it is: "Picnic in the Spring" by Shin Yun-bok (1758~?) from a collection of Gansong Art Gallery - Colors on paper.
The description on the back sais:
Three couple of young men and ladies are returning from picnic in the spring when azeleas are in full blossom. A lady with a spray of azelea in her hair, another lady waiting for a man light a cigarette for her, untidy behaviors of the men in a pleasant mood after spring outgoing match with the relaxed scenery of the spring to add deep atmosphere.
There's also a note for sender and recipient:
Sender: Please write on the back of the fan and include it in the envelope together with this note to send
Recipient: We hope for you to decorate your home with this piece or hang it on a wall to cherish sender's sincerity for a long while.
Which I happily did :)