doing the math:

Hikki: 4,715,900

Ayu: 5,335,000 and that doesn't include Ayumix IV AOV, since trainspotter didn't know. Guessing Ayumix IV AOV sold around 150,000 copies, that brings us up to almost 5.5 million cds.

I'm pretty sure that's right. I figured Ayu's sales would be higher.