The Japanese soroban settled on one bead above the reckoning bar worth five, four below worth one. Beads are birch or boxwood turned biconal — each reads as a diamond in silhouette. The frame is ebony, near-black and mirror-finished; the rods are smoked susutake bamboo, with a dot marking every third one.

This system takes its layout from that instrument and its texture from the paper beside it: the shuzan kentei grade table, printed small and dense in mincho on cheap off-white stock, carrying a single vermilion seal. It is examination equipment — ruled, numeric, administrative.