After waiting in line with the autograph-seeking Teddy Demons, Harpy invites Sya to a pajama party, somewhat disingenuously promising it will result in more cheerful sleep. Sya can’t pass that up, but she needs more information on what a pajama party is…so she hops into the Demon King’s bed to “practice” such a party.
Jumping in bed to practice is an extremely misinterpret-able scenario for, say, Cleric, who also overhears Sya talking about demons and humans falling in love. As a result, his devotion to protecting Sya’s chastity overrides his loyalty to his lord, and he attacks Twilight with lightning. The battle eventually gets too loud for Sya to sleep, but upon returning to her room she gets the cheerful sleep she sought…precluding the need to attend the real party.
Poor Harpy…she just wants to be friends with the princess! The succubus Cubey, on the other hand, has an ulterior motive: she wants to become more popular (popularity literally being the life blood of Succubi). When she learns she and Sya closely resemble one another, she seeks Sya’s tutelage on how to be more popular.
Unfortunately for Cubey and like most things regarding Sya, she isn’t popular on purpose, it just happens. Also, Sya misunderstands Cubey’s intentions from the start, believing her to be a potential body double in need of elite training. This results in Sya tying Cubey up and dragging her around the castle causing havoc, from murdering ghost shrouds to plucking Quillodillo quills to…well, actually, brushing Teddy Demons is delightful!
By the time Sya has Cubey on a cliff overlooking the lava lake impressing upon her the importance of staring death in the eye, Cubey’s struggling and yelling causes the cliff to collapse, and Sya falls into the lava and dies…again. Cubey fails to become more popular or learn anything useful from Sya, but Sya’s quest to get better “rest” succeeds.
Finally, Twilight and the Big 10 are having another important meeting when Sya again busts in like she owns the place, parks herself at the table, and tents her fingers like a petite, adorable Gendou Ikari. Whatever they’re discussing in this meeting is irrelevant: she has a task for them: to determine why the quality of her sleep has been lacking of late.
Twilight brings in Hypnos, noted sleep expert, to determine the cause. He arranges so the group can watch Sya’s dreams in real time, and the culprit to her crap sleep is revealed: “D-Whatsit”, AKA Dawner, AKA Akatsuki, the hero. Out of a desire to hang out, he is relentlessly pursuing Sya in her dreams.
While Cleric has known for a while now that Sya’s fiancée D-Whatsit and Dawner are the same person, both Sya and the rest of the Demons only come to this realization while her dreams unfold. Regardless of who he is, Sya doesn’t want anything to do with him, and shifts between attacking him and running from him. But like a chipper T-1000, he Just. Keeps. Coming.
Eventually Hypnos determines that Dawner is in Sya’s dream thanks to a letter bearing Sya’s signature…which Twilight learns he himself let fall out of his cape and into Dawner’s belt when he was redirecting the Hero’s party away from the still-under construction area of the Demon Castle grounds.
Once Twilight retrieves that slip of paper (not depicted on camera), Sya’s sleeping demeanor instantly improves dramatically to her usual tranquil “Syaaaaaa”-ing. And so, due to her acute aversion to the Hero, Sya further delayed her own rescue. But as we’ve seen, she’s not in any particular hurry to ever be rescued. She’s got the place on lock!