Boys' Day is also the male counterpart to Girls' Day, which is celebrated on April 3rd.
In big-city nuclear families, Boys' Day may be a simple affair, but in traditional extended families, the holiday is usually an occasion for an all-out feast where not only the family but also nearby aunts, uncles, and cousins get together.
Other than the food and good times, one of the best parts about Boys' Day is the koi-nobori, which are giant carp-shaped windsocks. Traditionally made of silk but today made usually of heartier nylon, these colorful streamers can be as long as 25 feet. They're usually hung from the top of a long piece of bamboo, or on a long rope strung horizontally. Some pictures of koi-nobori follow.