(I'll say right away, this isn't full canon or anything. These are just the author's guesses about what Saikou's family looked like when Fun Girl, here called Tanoshi (because that's how it sounds from the Japanese "Fun"), here you play exactly for Fun Girl when she was in the timeline as a living and existing being, but also, her character is approximate as could be)

Today the father and mother of the children were not at home, and they also reported that they might not be there for 4-5 days. So Ichiko prepared food according to the cookbook for her twin sister and her younger brother. She gave the plate of food to Ichiro and went to Tanoshi's room to take it to her too, but it was locked

Hey Tanoshi! Why don't you open the door to your room? All right? Ichiko asked worriedly, worried for her twin sister. Ichiro sat reading in the living room, pretending to be indifferent, though he was also worried about his older sister's condition