What is Ubuha(生ぶ刃)?
- Ubuha, also known as Ububa, refers to a 10cm unsharpened cutting edge area above the HA-MACHI(刃区). When a blade is newly made, polishers keep the area unsharpened on purpose.
- The unsharpened edge becomes thinner during many times polishing and finally, it disappears. In other words, a sword with Ubuha is in the original condition or is used just several times.