In a sense, chopping off a finger is only to gain a writing equipment.

Nowadays a simple, “Hey, can I borrow your pen?” will do.

He definitely was not prepared. This is how to do it properly.

1) Do it during daytime in front of a large and sympathetic crowd.
2) Get a knife, an antibiotic, a painkiller, a white paper that is used in blood writing (made of strong fiber), bandage, a small box to keep the pinky, etc. And, you need a friend who will serve as a second person.
3) With a crowd roaring with a strong approval(in the height of party mood), defiantly pull out the knife. Raise your hand high as well, to show the pinky is attached at the start(some may lie by using a “trick” pinky).
4) Now, chop the finger off. The smallest one is usually the popular choice. The knife must be of strong kind that can sever the pinky and the bone. A small jacknife will not do it. A machete or a chicken chopping kitchen knife will work.
5) Grab the severed the pinky with the other hand. Using the same hand will be difficult. Get the paper. While the crowd is cheering and before the blood dries, slowly and quietly write down what you want to say.
6) Chopping off the finger is not the center of the act. What you write on the paper is important. The finger and blood serves only as the pen and ink. In a sense, chopping off a finger is only to gain a writing equipment. One can possibly chop off other part(manhood, for example) and try using it as a writing instrument but nothing serves as well as a pinky.
7) After finishing the writing, which usually carries a strong sentiment, lift it up so the people can see your writing. Some may give a poor grade on penmanship. Yes, there are some lofty scholars in the crowd who will, even in times like this, find faults with wrong use of word, spelling(many times Chinese writing, which is more scholarly, is used) and grammatical errors. Asians are harsh critics when it comes to writing and literature.
Burning the writing is optional but rarely done. Why burn something so precious?
9) Immediately after this heroic act, you must tell the crowd not to copy the act because some hot-blooded young ‘uns in the crowd may like to copycat and join the hero circle as well. Dissuade them. Not because you care about them, but because if they do it too then your “uniqueness” is lost; you will be one of the many who cut off the pinky instead of “the one”. Also, these inexperienced jokers would want to write something with their pinkies as well. More bad writings and confusing messages!
10) Pick up the severed pinky and put it in a box. It is not uncool to do it yourself. This is why you need a second.
11) Your writing should be given to the person in charge, who will lift up so that everyone can see. And, he should say something like “since our comrade has shown such sacrifice to condemn this situation, let’s do our share”, and start marching with the writing held up high.

This ritual is so outdated and passe that only old timers enjoy it in Korea. Also, pinky-cutting is so Japanese; Yakuza members must do this to join the gang. Times are changed. Young Koreans, like the rest of world, will go for body painting instead of pinky-cutting.

Ah, no. at least on the Japanese side, it wan’t. It was even not a big news and nobody spoke about that in my office.

But you can’t stop lunatics. I am even not sure if he was really angry about north korea.

Second, this in Japan was a solitary protest. The finger chopping in Korea was a product of familial encouragement (son and mother) and was part of a mob-style anti-Japan protest that also included instances of self-immolation.

(Not that this makes anyone who does such an act of political-inspired self-dismemberment any less nuts.)

I’m glad to say that in all cases the police rushed to intervene, and have often been successful.