Nagashi-bina is a ritual that takes place during Hina Matsuri, a festival that prays for the girl's healthy growth placing small figure paper dolls on rivers and streams. It is celebrated on the 3rd of march at Shimogamo Shrine in Kyoto and its origin comes from the Heian Period (794-1185).
The Japanese woman in the picture is wearing what is known as junihitoe, a 12 layer silk elegant kimono that court-ladies used to wear in Japan back in the 10th century.