The seventh day of July is Tanabata. On Tanabata, people write their wishes on small strips of paper and hang them on bamboo.
According to the legend, Orihime, the weaving princess, is only allowed to meet Hikoboshi, the cow herder star, once a year, on July 7th.

Orihime, the daughter of the Heavenly King, was especially skilled at weaving and worked hard at her craft every day.
The Heavenly King searched for a husband for his hardworking daughter. He introduced her to the hardworking cow herder, Hikoboshi, who lived on the opposite bank of the Milky Way. The pair were happily married. However, they got along so well together that after the wedding they completely neglected their work. This angered the Heavenly King and he separated them to opposite sides of the Milky Way. Later, the Heavenly King looked at the two separated lovers and felt sorry for them. He let them meet on the evening of the seventh day of July provided they work as hard as they had in the past. And so the two were only able to cross the Milky Way to meet on the evening of Tanabata.
In China, a festival called Kikoden arose, where people prayed to become as proficient as the Orihime of the story at weaving or other handicrafts. The festival spread to Japan and was combined with the ancient Japanese story of Tanabatatsume and became the current festival of Tanabata.

Long ago there was a festival to welcome the god of the water on the seventh of July. A woman known as Tabatatsume worked all night at a loom and gave the cloth she had woven to the god as an offering, with prayers that there would be no disease or misfortune.

The evening of the seventh of July was called shichinichi, but became associated with 'Tanabata' of 'Tanabatatsume,' and so came to be read 'Tanabata.'.

Bamboo is used because it faces the heavens and grows rapidly. People felt that by entrusting their wishes to bamboo it would reach the heavens. We hope all of your wishes reach the heavens. ☆☆☆