Interesting name, that’s long been tied to possible Illuminati/New World Order satanists. The links here give some background on those theories, some of it is really far out, but likely contain an element of truth.
https://nihon-fanon.fandom.com/wiki/Order_Of_The_Black_Sun
https://www.auricmedia.net/the-black-sun-and-the-vril-society/
Very interesting. Thanks for the links.