Germany has historically maintained a complex relationship with adult media censorship. Under German youth protection laws (such as the Bundesprüfstelle für jugendgefährdende Medien or BPjM), extreme erotica and media depicting heavy sadomasochism face strict marketing regulations.
If you are following a specific niche self-published series on Amazon.de, this author is a likely candidate, though a 17th volume has not been broadly indexed. Der Sadisten Zirkel 17
: Series with titles like "Zirkel" (Circle) often fall into the psychological thriller or dark suspense categories, focusing on secret societies or clandestine groups operating outside the law. this author is a likely candidate