Not sure where to post this but there's a site that tracks weekly iTunes Japan top 50 best selling tracks and Ayu's charted a few times recently.
14/12/22 #13 Movin' on without you 浜崎あゆみ 6,896 / 6,896
14/12/29 #28 Movin' on without you 浜崎あゆみ 1,925 / 8,821
15/01/19 #50 Movin' on without you 浜崎あゆみ 739 / 10,707
14/12/29 #20 Zutto... 浜崎あゆみ 3,601 / 3,601
15/01/05 #20 Zutto... 浜崎あゆみ 2,966 / 6,567
They only show the tracks in the top 50 so they've sold more than that but it's cool to have some figures since digital sales in Japan are always so hard to track!
http://www.tnsori.com/