EXTENDED A/N
In "Forest of Thorns," Episode 10, we learn that Seiko Kasuga had a lover who grew up to be the headmistress of Lilian. The two girls made a suicide pact, swallowing pills. They both recovered, but the paper mistakenly said one had died, and both girls were told by their parents that the other one died to keep them apart. Kasuga-sensei wrote a novel about their experience, Forest of Thorns. Lilian staff thought Sei Satou wrote it because the pen name used was "Shuga" Sei and Satou in English is "sugar." Anyway, the two lovers re-met in Ep. 10, and this parody is set after they met. Also, the headmistress brought her in because Yumi and Seiko are fellow lesbian tell-all novelists at Cosmos and she is there to help interrogate Yumi. By the way in this story White Rose Sei Satou DID co-write the book, Yellow Rose Eriko WAS doing prostitution on dates and Yumi really WAS being summoned to the office for misbehaviour, not just to meet Yoko. So Kashiwagi and his car being there is a red herring. All the misunderstandings in the first few volumes are retconned as the office being correct about the scandals.
It's a pretty niche story: you have to know Marimite really well to get the references, yet not be offended by cheeky parodies of it. So I am glad some people liked it. You probably also have to be familiar with Irish rebel films/books. I don't know if this was clear, but the conceit is that every single scandal the office thought the Yamayurikai were involved in was completely true and exactly what they thought it was, but the girls talked their way out of it, every time.