Yubitsume
The manner comes originally from the Bakuto. If a gambler couldn't pay back a debt or something like that the persons tip of the little finger got cut off, which damage the hand and the person could not hold his sword as well as before. Also that way other people could see if a person haven't paid a debt, which could bring certain problems, since gambling always been prohibited in Japan. Yubitsume is when you cut of one of your fingers and send it to the Kumicho. This is done as an apology for disobedience. It can be done to atone for a wrongdoing but can also be done to spare one of your "children". When you have done something that your Kumicho dislikes you take a sharp item, cut off a fingertip, wrap it in paper and send it to the Kumicho and beg for his forgiveness. If it's the first time you cut off the little fingertip there after it becomes the next little finger and so on. Because of that you may see yakuza members that are without several of his fingers. This helps often at wrongdoings, but if you've done something all to seriously, as e.g betray the entire clan, there´s nothing that can help you from becoming a statistic.