How do you quilt a large sashiko quilt?
It's a dilemma. You don't want to machine stitch over your hand stitched work, but you also don't want the filling and backing layers to separate from the top. And you really don't want the filling layer to bunch up or fall apart because it isn't quilted.
Over the years I have used different methods, depending on my project. This one, using pre-quilted batting, is easy and suited to almost any sashiko project, I think. It uses pre-quilted quilt batting.