“The term “Yakuza” comes from a Japanese card game, Oicho-Kabu (played with hanafuda or [kabufuda] cards). The worst hand in the game is a set of eight, nine and three. In traditional Japanese forms of counting, these numbers are called Ya, Ku and Sa, thus the origin of the word “yakuza.” The yakuza took this name because the Ya-Ku-Za hand requires the most skill (at judging opponents, etc.) and, obviously, the best luck in order to win. The name was also used because it signified bad fortune, presumably for anyone who went up against the group….
Yubitsume, or finger-cutting, is a form of penance or apology. Upon a first offense, the transgressor must cut off the tip of his left little finger and hand the severed portion to his boss. Sometimes an underboss may do this in penance to the oyabun if he wants to spare a member of his own gang from further retaliation.
Its origin stems from the traditional way of holding a Japanese sword. The bottom three fingers of each hand are used to grip the sword tightly, with the thumb and index fingers slightly loose. The removal of digits starting with the little finger moving up the hand to the index finger progressively weakens a person’s sword grip.
The idea is that a person with a weak sword grip then has to rely more on the group for protection — reducing individual action. In recent years, prosthetic fingertips have been developed to disguise this distinctive appearance.”