Tanabata is a Japanese tradition wherein people write their wishes on tanzaku papers (colorful, small strips of papers) and hang them on bamboo branches. People also decorate bamboo branches with various kinds of paper decorations and place them outside their houses.
It's said that tanabata's origin dates back to more than 2,000 years ago with an old Chinese tale. Once there was a weaver princess named Orihime and a cow herder prince named Hikoboshi living in space.