Umineko: When They Cry gives us Battler's stepmother Kyrie Ushiromiya. Being a huge Yandere actually saved her life in the duel with Leviathan of Envy. When Levi tells her how she envies her sisters for being born faster, Kyrie just says "So you envied your sisters for seven days? Okay, that's fine and dandy. But what about me? I envied some bitch for eighteen years for being the wife of my man! HOW IS THAT?!" and shoots Leviathan dead. In Episode 6, she tells her niece Jessica in that if Battler's mom Asumu didn't die on her own then she would have just killed her, all to be with Rudolf.
"No, her death was a predetermined fact. If she hadn't died, I would have killed her. The miracle was that I didn't have to stain my own hands."