On 7th July is always fun for children. Tanabata is a very old custom event held in all over Japan.
The history is way back to Nara era (710). It was a popular in nobles at the beginning then this event were slowly spread to common people. Its based on the story that Hikoboshi and Orihime. Apparently there is few theories but this is what I've heard when I was a kid.
Orihime (Vega) were only daughter of the god, she's talented to make a beautiful textiles.
When she became a certain age, the god were start to look for a man for Orihime to get married.
One day, hard working young cattleman called Hikoboshi (Altair) were introduced to god and god has approved their marriage.
Both Orihime and Hikoboshi were so in love each others, however after they got married, they were not working hard as used to be. One day god were very upset with both of them and he split this couple and run the really wide river called Amano gawa between them.
Since then, Orihime and Hikoboshi were not allowed to see each others, but both can cross the river to see each others once in a year, which is 7th July.
(Vega and Altair is shining across the river...)
So for the children usually decorate bamboo with cut out colorful Origami.
Also write their wish on small strip of paper and attache to the bamboo.
Yesterday, Japan were officially announced the end of rain season and beginning of summer. Hopefully sky will be clear in the night, otherwise Orihime and Hikoboshi can not cross the Amanogawa...