Uchiko's Sasa Matsuri—or bamboo festival—is a major part of the town's calendar for months before it starts. Businesses, schools and local officials all get together in their separate groups to prepare decorations for the main street. The decorations are called sasa gazari, or bamboo decorations. Pieces of colored paper are arranged on a ball-shaped bamboo framework, and the balls and the paper strings that hang from them are then suspended from thick bamboo poles. The poles bend over the main street, veiling it with the colorful decorations.

While the whole town is involved today, it's the businesses of Uchiko that established the festival. They wanted to thank their customers for their patronage and so started the decoration tradition in 1957. It falls with the Tanabata festival that is celebrated all over Japan in July or August.

During Sasa Matsuri, 1.5 kilometers of the shop-lined main street, decked in every color of the rainbow, is the venue for events like a yukata contest and a children's lantern procession on the first day, and the main event of teams dancing the traditional sasa odori down the street on the second day. Onlookers bunch together to watch the dancers and shout encouragement—dancing for an hour or more can be exhausting! The dancers' moves and costumes are evaluated by judges who sit at tables along the way. Events on the third day include taiko-drum performances by various local groups in the Uchiko theater.