Tanabata originated from a Chinese legend called Qixi and was brought to Japan in the 8th century.
This is the story of two lovers. Princess Orihime, the seamstress, wove beautiful clothes by the heavenly river, represented by the Milky Way. Because Orihime worked so hard weaving beautiful clothes, she became sad and despaired of ever finding love. Her father, who was a God of the heavens, loved her dearly and arranged for her to meet Hikoboshi, the cow herder who lived on the other side of the Milky Way. The two fell in love instantly and married. Their love and devotion was so deep that Orihime stopped weaving and Hikoboshi allowed his cows to wander the heavens.
Orihime’s father became angry and forbade the lovers to be together, but Orihime pleaded with him to allow them to stay. He loved his daughter, so he decreed that the two star-crossed lovers could meet once a year--on the 7th day of the 7th month if Orihime returned to her weaving. On the first day they were to be reunited, they found the river (Milky Way) to be too difficult to cross. Orihime became so despondent that a flock of magpies came and made a bridge for her. It is said that if it rains on Tanabata, the magpies will not come, and the two lovers must wait another year to be reunited, so Japanese always wish for good weather on Tanabata. There are many variations of this story, but this version is the most widely held.
We hope for clear skies on Tanabata so the lovers can always be reunited.
Video credit to Fukumusume Dowashu, Youtube: mtanakaunis