Oricon made it official with the first tracking week of #Sukinanda pushing their total sales record to 51,298,000. Ayu still holds the record for best selling female solo artist with an amazing record of 50,675,000 units, however, Oricon doesn't differentiate between solo artists and groups under the male and female categories.
The current Top 3 of the best selling female Japanese artists of all time is:
1 51,298,00 AKB48
2 50,675,00 Ayumi Hamasaki
3 39,581,00 Yumi Matsutoya
source:
Article from Aramajapan which is based on Oricon itself.