In Vietnam, Below 10 years old to 40s are populous generations, which is very different from Japan where the proportion of people in their 40s to 70s is large. 

United Nations ”World Population Prospects 2022”
Retrieved February 9, 2023, from https://bit.ly/2URh0vE

In Vietnam, Below 10 years old to 30s are populous generations, which is very different from Japan where the proportion of people in their 40s to 70s is large.

Reference United Nations ”World Population Prospects 2019” Retrieved June 15, 2020, from https://bit.ly/2URh0vE