Bummer. DLSite Japan no longer accepts US credit cards. AT least, not my Visa Debit card.
Weird, I've used my US credit card on DLSite Japan multiple times in the last few weeks.
It might be that I have Verified by Visa setup on my card. I know that Nico Nico Douga Japan only accepts US credit cards if they have Verified by Visa. Could be a trend.
I'll give it another try I suppose then, maybe it was just bad luck.