These trees were planted to commemorate an engineering project. The Ohkouzu diversion is an artificial channel, cut to send part of the Shinano river straight out to the Japan Sea instead of letting it run down through the plain, and Niigata's tourism authority says the Somei-yoshino along it were planted in tribute to that work.

They stand on the embankment that holds it in.

An embankment is not built to carry water. It is built to stop water going somewhere, which is a different kind of structure with a different reason for existing, and the cherry trees are on top of it. The flowering runs from the first part of April into the middle of the month.

Walk the avenue and the two sides of it are not the same. On one hand there is the diverted river, wide and fast and doing the job it was dug for. On the other there is flat farmland that is dry because of it. The trees are the celebration of the difference between those two views, planted along the line that produces it. Walking the avenue means walking the line that separates them. During the Tsubame cherry festival the trees are lit from six in the evening until ten, and after dark the two sides go dark at different speeds.