There are countless rivers flowing from the mountains to the sea in the Japanese archipelago, and it has been closely related to life for a long time. The wide riverbed, which alleviates the flooding of the river and becomes a valuable square for residents, is unique to Japan!? ▽As a place to relax in a big city, a cool river revives in the valley of the building!? ▽What is the tradition inherited by the precious nori and food culture that inhabits a specific river? ▽High school students revive the river contaminated by domestic wastewater with handmade equipment! The way of thinking of local residents has also changed. From tradition to the cutting edge, is the Japanese river cool?