Yakuza cut off the top joint of their little finger when they make a serious mistake, do something that embarrasses the gang, costs the gang money, or causes dissent within the ranks. It is also a way to apologize when you can't pay a debt, to end a feud, or to settle a dispute. The practice is called yubizume and is actually an old samurai tradition. When a Japanese sword is held properly, most of the grip's strength is applied by the little finger, so a person who had cut his off could not hold his sword properly. Samurai who could not hold their swords properly were far less effective in battle, and thus, more dependent on their lord. The yakuza adapted the practice, because many of them consider themselves to be following the old samurai traditions.

If you don't want to know the gory details of how yubizume is performed, stop reading here.

The process is designed to be as unpleasant as possible, helping the yakuza show how sorry they are. They always do it themselves. First they take a string and wrap it tightly around their finger so that it cuts off the circulation. This both numbs the finger and lessens the amount of blood they lose. Originally yubizume was performed with a knife but now it is usually done with a square shaped, very sharp chisel called a nomi. They put the chisel above the first joint, and give it a good whack with a heavy hammer. The finger usually flies 20 or 30 centimetres, which gave rise to the expression, ·Yubi o tobasu·(make your finger fly).

What do you do with your finger when you've cut it off? You present it to the person you offended or to the kumicho (leader of the gang). In his book, Uyoku, Yakuza, Sokaiya: Honto no Sugata, former police officer Ishigumi Takao relates the story of how he visited a yakuza headquarters and went to get a drink. One of the yakuza told him, "Please don't look in the fridge." When he asked, "Are everyone’s fingers in there?",·the man gave him an embarrassed nod.

The stupidest finger-cutting story you will ever hear was told by Inagawa-kai president Kakuji Inagawa. He relates how he tried to stop the practice of yubizume but some of his lieutenants just didn’t get the message. When one of them demanded that one of his low-ranking gang members cut off his finger for some serious infraction, the oyabun got angry and berated the boss. The boss, comprehending, but yet not comprehending, cut off his finger and sent it to Inagawa by way of apology.

The practice of yubizume is gradually dying out, both because yakuza do not want to be easily recognisable and because the samurai values that were once so important to them are fading out. Nowadays a yakuza is as likely to offer money to end a dispute as he is his finger.