Blood Sale is that people sell their blood to the people who need blood and earn the money from it.
The most people who sell their blood was not able to get a job, so they wanted to make money from it.
Selling blood is too easy to make some money than work,so many people had depended on it.
As a result, it has been said that "Yellow blood " and the number of people who are called was increasing at that time.
Yellow blood is the color of blood changes to little yellow.
If you do too selling blood, the number of erythroid in the blood decrease.
Also the number of plasma decrease too.
Plasma is little yellow,so the blood chage to little yellow, so it is called "yellow blood".
If people give a blood transfusion, the blood which was collected by the person who does too much selling blood caused pneumonia. Also, it was a big social problem.
Also selling and buying blood was criticized. Because the thought was increasing that selling and buying blood may be connected with human traffic.
As a result, it had happened some anti-selling blood movements.
And then the Japanese government decided "promotion of donation of blood" in 1964. And Red Cross Blood Centers were built at the whole country.
Blood selling by the low-income persons cause "Yellow blood " and it had been a big problem.
Therefore many blood centers were built at the whole country to help not only the patients but also the low income persons.