It's impossible that she sold almost 40 million outside of japan.
I would guess she's closer to 60 than 50 now, but not 100.
as of 2005 for japan (from music station)
From Music Station 2005.04.01
Rank Artist Sale
1 B'z 75,614,000
2 Mr. Children 50,635,000
3 Southern All Stars 47,083,000
4 Hamasaki Ayumi 45,528,000
5 DREAMS COME TRUE 40,893,000
6 Matsutoya Yumi 37,790,000
7 GLAY 35,800,000
8 ZARD 35,450,000
9 Utada Hikaru 32,160,000
10 CHAGE & ASKA 31,220,000
Actually I¨m not sure if she passed SAS yet, but it's possible which would make her the third most selling japanese artist domestically of all time. THese are oricon's numbers.