According to
https://ipinfo.io/, Aien Hime's websites are on a server in the Netherlands with an IP address of 85.92.140.22, which has 74 other domains listed. I could load the linked address for most of the 25 sample domains provided. However, four domains from this sample (one of which is aien-hime.com) returned a "server not found" message. A fifth domain returned a "500 internal server error" message.
I don't know why these domains couldn't be loaded, but the problem affecting aien-hime.com isn't exclusive to it. For example, there could be a problem with the server itself, causing access issues to some of the websites it hosts.
It might be worth someone directly messaging Aien here (if they haven't already) to see if she knows anything.