How do I get Preppy Girl's secret idol ending? It was listed in the guide, but there are no clues towards getting it.
I'm pretty convinced it has something to do with gangbanging the idol while Preppy is at the dance floor. Get permission to see Takano, she'll tell you to go breed the idol, but then you start Preppy's quest, and do it all until she gets to the dance floor, then breed the idol before her eyes. I didn't tried it, but that's my wild guess.