Cultural Thing: The Finger Removal Practice

I was reading about the art of tea when I ran across a reference to a story about Yoshitsune, the hero of Arthurian type legends in Japan. In one of the Japanese monasteries, Sumadera Monastery near Kobe, there hangs a tablet that has the following quote after reference to the beauty of the blossoms states, "Whoever cuts a single branch of this tree shall forfeit a finger therefor."

I immediately gave thought to the practice of the Japanese Yakuza where one who has done something that requires atonement to a senior would therefore cut off a piece of the finger. Is it possible that this old Chinese tale inspired this particular act of attrition. When you couple the many influences of China and such as Confucianism, Buddhism and Zen along with the great effort to incorporate such things into the Japanese culture and customs it is not farfetched an idea, is it?

We know that it is a custom for Yakuza so say the different cultural writings in English - translated. We don't know the origin of the practice or if it actually extended from the feudal era of great influence to Japanese culture and beliefs. It may be that even the Japanese, specifically Yakuza, know of its origins but it is an idea as to a possible source, yes? 

Additional Information: http://en.wikipedia.org/wiki/Yakuza

Yubitsume [Yubitsume (指詰め, "finger shortening")], or the cutting of one's finger, is a form of penance or apology.

This article alludes to its origins in swordsmanship: "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." Is it possible the idea still comes from the origin above?

It also stated, "The idea is that a person with a weak sword grip then has to rely more on the group for protection—reducing individual action." This falls into some of my studies in that one who is a bit of a rogue or individualist is not complying with Japanese culture, i.e. the group is everything and to embarrass the group, etc. is taboo. If a swordsman did something not group approved, etc. then to do this ensures in a most physical way they must remain a member of the group where group decisions and actions have to have a group consensus, etc. It would also speak to the samurai in question as a reminder that death is there when one does not conform to the group. This does make some sense I think.

Remember, all things are to be considered with caution. I kind of like my hypothesis tho :-)

See also: http://en.wikipedia.org/wiki/Yubitsume