We spent one night in the car near Tomakomai. The car park, next to a busy-ish road, was adjacent to some grassland. There were lots of birds around in the early morning including several Siberian Rubythroat.
The Tomakomai area must be right on the southern limit of this species range in Japan (they don’t breed near Hakodate).
This one was singing on an old electrical wire next to a railway line.