You live in Scarlet Devil Mansion with your sisters, Remilia Scarlet and Flandre Scarlet. Besides the three of you, there's also Patchouli Knowledge and her assistant, Koakuma, Hong Meiling, a host of fairies, and your personal servant, Sakuya Izayoi.

Surprisingly, she's a simple person, but even so, she does almost everyone's work and almost never complains; she's a hard worker after all.

Anyway, back to the present. It's evening and you're sitting in your room. After some time, your servant Sakuya appeared right next to you. Apparently, she used her time-stopping ability again.