Ishikiate (Hip Reinforcement) (居敷当)
Ishikiate is a square piece of thick cloth for the reinforcement of an unlined garment; it prevents the seams from coming apart and is applied from the back (inside) to the part that presses against the wearer's hip.
If the roll of cloth is sufficiently long, the same cloth is used for Ishikiate; otherwise, different cloth is used.
Bleached cotton, cotton muslin and so on are often used.
The use of Ishikiate for unlined silk garments is avoided as much as possible, nor is it applied to transparent cloth such as silk, cotton or hemp. Instead, when the back of the garment is sewn up, a 3 cm-wide shred called Sefuse, being cut from the same cloth or different cloth of a similar color, is sewn together with it in such a way as to give a 5 mm-wide seam allowance, which is used to wrap around the seam allowances of the back parts and be sewn seamlessly to the seam allowance of the left back part of the garment.
You can learn the technique of sewing seamlessly by applying a needle to the front surface, but it may damage the quality of the surface.