Shinogi is a decorative technique in which you make notches in the surface of the clay. It often involves a series of parallel grooves. The name refers to the ridge of a Japanese sword: a long line in the blade of the sword that runs from handle to tip.
This technique is not complicated, all you need is a sharp object and a steady hand. A few deep breaths in and out, and supreme concentration … and, who knows, some beginner’s luck?