Humans have been around for a long time.  In Japan specifically, humans have been traced all the way back to prehistoric times.
Wow, that's interesting! About how long have humans been around?
Well as far as Japan goes, the first written account of the Japanese goes, there is a "Book of Han" which dates back to the 1st Century.
What is the "Book of Han" about?
It refers to the Han Dynasty or the Han Empire.  That was the 2nd Imperial Dynasty of China.