This section is a collection of patterns on the square jigumi that don't really fit into any of the other groupings.
Kikkō-nishiki (Book 2; Kindle Vol.3)Kikkō means tortoiseshell, and the kikkō pattern is a hexagonal shape; nishiki is Japanese brocade, but here it is probably just a fancy way of saying pattern.
The pattern highlights the hexagonal shapes in the centre of each row. This is not simply a soraban pattern turned on its side; the angles are different so that the pattern forms a well-balanced hexagon. In the soroban patterns the eye is drawn to the soroban beads rather than the hexagonal shapes that form those beads.