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Nightmare Fuel: Smile Pretty Cure!
Episode 32; seeing all of the Cures smiling with Dull Eyes of Unhappiness is pretty unsettling. The dissonant music doesn't help.
That was actually a scene lifted from Yes! Pretty Cure 5, fitting, as Joker is an Expy of Kawarino, the one who brought that scene with the similar 'Nightmare Mask'. However, Joker gives a more nightmarish continuation and conclusion: if Nozomi could brought her friends back to their senses with mere words, Miyuki is forced to fight an Akanbe in a losing battle alone while her friends just watched with the same expression, and every of her calling out for them to wake up just fell to deaf ears. That's like you're in a nightmare and none of your screams of help do good to get you out of it, even if helpers and friends are nearby. Good thing Miyuki is a Plucky Girl and her refusal to stand down eventually broke the spell.
Many consider Joker to be this himself. Especially some of his expressions.
Episode 43; while Joker Breaks Reika By Talking and mentions her two selves—Cure Beauty vs Reika, he shows her a giant mirror. Beauty looks into it, seeing her reflection...and Joker briefly takes control of it, so now her reflection has his creepy Slasher Smile and wide eyes. And talks in his voice.
Episode 46; Joker again. This time it's his Villainous Breakdown when the Cures defeat his Psycho Rangers and reappear to take him on. The faces he pulls, as well as the animation, are just freaky. Then as if that weren't bad enough, he turns into the ink used to collect Bad Energy, making him an inky monster in the vague shape of a human, with only his grinning mouth to be seen.◊