Sashiko threads skeins have to be opened out before use. Slide of the skein band first. You will find all the thread is tied together at one point.  Cut through the skein at the knot, so all the threads are cut (you'll find these are the ideal length for stitching doubled).  Push all the thread through the skein band, and then plait the thread loosely.  Pull out each thread as you need it from the loop end of the plait, not the 'fringed' end. This saves time trying to wind the thread into a ball, keeps it tidy and you know the thread shade number if you need to re order.