Why is the mailbox in China green and the mailbox in Japan red?

Green is a special symbol of China Post, symbolizing peace, youth, prosperity and prosperity.

The post offices, postboxes, clothes of postmen, postal parcels and postal vehicles in China are all green.

After Meiji Restoration in Japan, he was the first to learn French Post.

The mailbox is black. (But then France changed to yellow, too. )

But before the conclusion of anglo-japanese alliance, Japan fully followed the trend of Britain.