Kogin is a type of stitching that somewhat resembles Norwegian smøyg or counted thread embroidery. Geometric patterns are created by covering areas of fabric with horizontal stitches, counting between the loosely woven fabric and building up the pattern row by row.
Learn more about the technique here.
These kits contain a needle, thread, wadding, fabric, and instructions (illustrated chart with Japanese text - see the link above for general guidance) for 1 pincushion.
You can also fill with other materials, or other materials in combination with the included wadding if you want more weight, or something that "sharpens" the needles (like sand, walnut shells, steel wool, or similar). If you fill with something other than wadding, it might be a good idea to place a layer of more tightly woven fabric under the linen after you've finished embroidering, before you cinch it up with the filling, since the linen fabric is loosely woven to be suitable for kogin stitching.
Finished product measures approx. 6 x 6 x 3 cm