FOOD Kashiwa-mochi, A rice cake(In the Kanto district)
Chimaki(A rice dumpling(In the Kansai district)
TIME May 5
"Tango" originally means the first day of the Ox. But May 5 has said to be "Tango" since era of the ancient China. Most of events in Japan are introduced from China, and they include Japanese customs. So they have become the event to drive away one's evil.
In Edo era many families ,especially samurai families which have boys under 7 years old setted up the flag of May outside of their house, and displayed the doll of an helmet. In the middle of Edo era they setted up a carp streamer.
As for food, we eat Kashiwa-mochi and Chimaki. Kashiwa-mochi is a rice cake wrapped up in an oak-leaf, and is eaten in the Kanto district. Chimaki is a rice dumpling wrapped in bamboo leaves, and eaten in the Kansai district.