Here’s the dlsite
And for the ci-en, you have to subscribe to jashinn to download the game and the same goes for fantia.
If you have difficulty purchasing on dlsite, here’s what jashinn said:
You can use your credit card at Ci-en ヾ(ヾ(•ω•`)o
First you can go to the page to buy points:
https://www.dlsite.com/maniax/mypage/user/buy/point
Then select For Books (you will need to sign up for a For Books account).
Then select “More payment options” and use Card.
And this might help