The Green Town endings are only available by killing the sorcerers and parting ways with Evil. Staying with Evil or keeping all sorcerers alive will lock you out of those endings. I'm going to assume you don't mean the slime girl's scenes and you're actually talking about another CG. Before you kill all the sorcerers, go to the magic shop in the city and purchase an artifact. You'll then start the newest available content. Save as you go, because there's many path deviations from here on out that lead to different endings. If you rather not experiment and explore every path, you can follow the guide I wrote on
#767. Obviously there will be spoilers.