@Boomthorkell If anything I'd say it was just the first one to make it "big" or "to mainstream TV" or something like that.
To give just an example, Re:Monster had goblins kidnapping and raping girls since the very beginning too, and it was in the manga. And the novel is 5 years earlier than GS. But since there's no anime...
But okay, you've still got a point. Even if there's a few dozen works (and that's not even counting Hentai) that were already doing this before GS was even conceived as an idea, it's probably the first to reach the mainstream media, so...