Try your luck with a different VPN or browser. You might need to be signed out of your account without any previous cookies in order to trick it, but I don't know for sure because I haven't tested that myself. I use a second browser for my VPN needs. DLsite did this due to their credit card debacle, where VISA and Mastercard bailed out due to school girl and loli content and for a while were unavailable as purchase options requiring westerners to buy points through 3rd party retailers and use those to purchase games. They were reinstated recently but apparently the humiliation ritual for DLsite is that they have to censor some titles in the west, like loli and school girls especially.