Tenugui that has been around for a long time (one theory says that it has been used since the Nara period).
Originally, tenugui is a cloth mainly for wiping sweat and water, and for washing the body when taking a bath.Since it is easy to dry after use, dirt does not collect on the edges of the cloth and it is hygienic. It seems that it is left uncut without being sewn by bending it.

In addition, because it is used as a first aid by tearing it into bandages or thongs, it is left uncut at both ends without being sewn.

This is not limited to Tenugui Kamino's Tenugui cloth, but in general, it is standard for "Tenugui" to be left uncut.

If both ends are left uncut, the thread may fray or unravel, but if you wash it to some extent, it will stop fraying about 1 cm from the edge of the fabric.
Therefore, the thread does not fray or unravel little by little, and the towel does not become extremely short.
If you are worried about fraying or if the thread comes out and is dirty, cut it off with scissors.