The metaphor in this statement is "the great millstone" it kind of qualification word it express how big the time was.
But in reality, millstone doesn't even have a relationship with the time.
So "the great millstone" is a metaphor.
Nisei means- second generation. Used in japan for second generation people born in North America with Japanese heritage.
Heloooooo!!!!ฅ^•ﻌ•^ฅ∠( ᐛ 」∠)＿
