[Impracticable]

the point of this is NOT to tell you the top 5 of all time. there is already a thread in the news section of that ... its to tell you what the estimated sales would be if they all debuted in the same year [im going to be using 1978 for the year ~~)

Spoiler:

The real list of top 5:
1. B'z (75.614 mil) 1988-now (average: 3.979 million a year)
2. Mr.Children (50.635 mil) 1987-now (average: 2.531 million a year)
3. Southern All-stars (47.083 mil) 1978-now (average: 1.623 million a year)
4. Hamasaki Ayumi (45.528 mil) 1998-now (average: 5.056 million a year)
5. Dreams come true (40.893 mil) 1989-now (average: 2.271 million a year)

The estimated list:
1. Hamasaki Ayumi (146.624 mil) 1978-now (average: 5.056 million a year)
2. B'z (115.391 mil) 1978-now (average: 3.979 million a year)
3. Mr.Children (73.399 mil) 1978-now (average: 2.531 million a year)
4. Dreams come true (65.859 mil) 1978-now (average: 2.271 million a year)
5. Southern All Stars (47.083 mil) 1978-now (average: 1.623 million a year)

so this means ayu could probably become the top selling japanese artist ever soon ...