Evil Coop goes on a rampage throughout the mall, but the evil also spreads to Yin, Coop goes back to normal after Yin calls Coop "sugarbeak." Meanwhile, Yo tries to get the bow-tie and suspenders by beating a clown in Clown Foo. When Coop turns the city bad he then realizes that Yin won't ever be with him if he causes destruction, he decides turns Yin evil so she will accept it. After going on a mindless rampage the Coop and Yin decide to become Night Masters. Yin is told that she is not evil enough to become the Nightmistress and is intent on destroying Yang to gain her entry to become the Night Mistress. During the battle, Lina and Yang (well, actually just Lina, since Yang admitted long ago) admit there feelings for each other. Just when Lina and Yang are about to be wasted, Master Yo shows up and drains the evil out of Yin. Good Yin then convinces Evil Coop to turn back to normal. Yang and Lina starts to develop their relationship.
She rudeless and mean.
- In "Gone-A-Fowl", Yin becomes affected by evil, which changes her appearance.
- After touching Coop in his dark form the first time, Yin wears black eye shadow, black lipstick, black training vest and black hair bow as a bad girl appearance.
- In her second dark form as Gothic Girl, Yin's fur is white and has a head full of black hair. She gains a black tank shirt, black pants, black skull earrings, black bracelets, spiky neck strap, and black boots.
- In her final evil form, she gains dark purple kabuki style face markings and her eyes become yellowish-orange with black whites. Her fingers become pointy, her long ears are a little fuzzy (sort of like Yuck's ears), and her teeth become razor-sharp. In her aura form, her aura is purple and has red eyes.