The Hiikawa is the river of the Yamata-no-Orochi story. Along its embankment at Kisuki there are about eight hundred Somei-yoshino over roughly two kilometres, which Shimane's tourism authority describes as a tunnel of blossom. The flowering runs from late March into the first days of April, which in this part of Shimane is the start of the farming year. Unnan city puts the wider count, taking in the town centre and Kisuki park up on its hill, at around fifteen hundred trees in total.

An embankment is earth piled up in order to hold a river down.

This one has had reason to exist. The Hiikawa has a long record of flooding and has changed its course more than once, and the eight-headed serpent of the myth is generally read as the river itself.

So the cherry trees are planted on a defence: along a line drawn against water that the people here have had reason to fear for a very long time indeed. At night the lanterns come on inside the tunnel and the whole two kilometres lights up from within, which from across the water reads as a lit seam along the bank. The bank built to keep the river in its place has ended up as the busiest walk in the town, for two weeks a year.