You have to understand that this game's community invites and harbors a large assortment of frustrated, toxic and sometimes extremely mentally ill individuals, some who get off almost exclusively on hurting others.
It's pretty obvious that this person is only continuing this behavior because they find your reaction funny. They probably don't see you as a human being because they've decided by themselves that having a different sexual orientation makes you inferior, and with no avenue in real life to vent their beliefs because they'd be immediately shut down, they turn to the internet where they don't fear consequences to harass people, which in this case is on an unmoderated Japanese hentai character card website. Let that sink in, because there's not much lower a person can go bud.
You should know the vast majority of the people who use this website have been using it for years, and frequently view the front page to download all of their content, so anyone interested in your cards would obviously find them there. I know it's frustrating, but you'll need to ignore the behavior. It's obvious that it's the same person, "samefagging", to try to make you feel like you're alone and that nobody wants you here. Rest assured that's not true and it's obviously the behavior of 1 very disturbed person.
It's the internet bud, the mental illness capital of the world. Hope that makes you feel better.