: The central figure is typically depicted as a "mature female" or "MILF" character. Key visual traits in AI training data include black hair styled in a single hair bun or low ponytail , yellow or brown eyes , and occasionally slit pupils .
You were likely looking for Oshi no Ko (not Shinseki no Ko), and the specific "sleepover" content usually refers to the hotel scenes during the Tokyo Blade arc or fan-created spin-offs.
And I thought: Yeah. Best work ever.
Often features a "cool" or mischievous female lead contrasting with a more passive or easily flustered male protagonist.