Single sales in Japan (at least for female artists) have been dropping forever. I wouldn't be surprised if it only sold like 20k....and the sad thing is, those would still be amazing numbers compared to 90% of artists in Japan.
I feel like I say this every time there is a release, and people still freak the fuck out anyway.
Singles will be obsolete in Japan one day, at least going the way of digital downloads, just like they are here in the US. It's just taking a lot longer because they've had years of culturally loving them.
And all the Frozen talk. Be happy for Avex that they own all Disney distribution rights and that they're making money. It'll cover failings elsewhere