That's what you're not understanding, You're not finding anything because the Asian cultural paradigm is different. They don't have a Western concept of good and evil. Instead, you might find things that are unlucky that are avoided, but honestly, no "evil" group will use an unlucky symbol, either.
Instead of trying to warp Asian culture to fit the Western paradigm, work with it. Even "evil" gangs will choose a symbol that is auspicious to them. If you need to make it glaringly obvious, try something like a black lotus or a black peony. The black can be your "evil" while the flower is traditionally used on banners, in kamon, and on fans.