Why is the Japanese mailbox red?

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. The mailbox in Britain is red. It was 190 1 studied in Japan. By 1908, the Kuomintang has changed to a red mailbox.