Shichi-go-san is a Japanese event to celebrate the children's growth when the girls turn three and seven years old and boys turn five years old. Thus, the event is called Shichi-go-san, which literally means seven, five and three in Japanese. This event happens in the middle of November.
Many parents put the Kimono (traditional clothes) on the children and visit a shrine to pray that the children will keep growing healthy.
Children get a sweet called Chitose-ame, which is a white and red color and long-shaped candy. The Shichi-go-san started in Heian Era (8-12th century) and the practice of Chitose-ame eating started in Edo Era (17-19th century).
If you visit Japan in November, you could encounter small children in Kimono at a shrine.