Since around 7th century, the Japanese imperial headquarters have introduced this system.
The Japanese take advantage of any opportunities and try to make money.
In a sense, it is quite reasonable.
When I was a worker of a Japanese company, I thought that the company could employ a manager with a very low wage.
I thought that there were quite a few rich people unemployed.
They didn't need money. But they wanted honor.
In fact, the company employed an a little stupid female girl.
I was told to take care of her because she was a daughter of an important customer.
Particularly in the case of government workers, they receive more than 300 million Yen (equivalent of 3 million dollars) in their lives including wages and pensions.
If the government demands the bribery when they are employed, it will be quite easy to get a large money from them.
Japanese are originally economic animal and it was a matter of time for them to introduce such an official monetary system.
Nowadays in Japan, bribery in entering a university is said to be common. But such a tradition would be the tip of the iceberg.
Of course the bribe is prohibited by the law, but there are many loopholes.
As there are few related English pages, I would put some Japanese site. You can understand the meaning by translation.
"Baikan system" can be English translation.
You can read related English pages through a Google search.
https://www.google.com/search?q=%22baik ... e&ie=UTF-8