“Tango no Sekku” or “Kodomo no Hi”(Children's Day).
In Japan, the carp is thought to be a symbol of strength, courage and success because of a Chinese legend that a carp swam upstream and became a dragon. "Koi no Takinobori (Carp's waterfall climbing)" in Japanese proverbs, means "to succeed vigorously in life." Nowadays some families not only raise carps for their boys, but also raise one for dad, one for mom and each for each kid. The flags blowing in the wind look like carps are swimming. When you see the flags in the sky, the summer is not far away. Kashiwa Mochi (rice cakes wrapped in oak leaves with sweet beans inside) is one of traditional foods that are eaten on this day. Another traditional food is Chimaki, which is introduced from China, steamed sweet rice wrapped in bamboo leaves. If you want to view the carp streamers in Tokyo, Tokyo Tower is definitely a good option. There holds a Koinobori Event during Children’s Day period. The wire tethering the 333 Koinobori will glow in 7 different colors! At night, they also light up! Thank you to this site for providing information about Boy's Day: https://www.hisgo.com/us/destination-japan/blog/tango_no_sekku_-_boys_day.html