There may be precursor scenes to these because I remember Rina's sleeping being discussed but I started recording these going to every possible house location at each time after all the other scenes were found. The occur seemingly random, but trigger when you visit a location, regardless of where you see the girls elsewhere in the house. It seems you have to get the first scene in the series before you have the option of seeing the next. No idea if time of day matters, I expect for at least some of them they do. You may need max stats (20, 40, 40) as of version 0.4.4.1
- Evening Dining Room with Rina. Rina is asleep at the table
- Morning Living room with Hana. Hana mentions Rina being overly tired.
- Morning Living room with Rina. Talks about Rina's sleeping
- Night Rina's room. Rina gives you an option
- Morning Your Room with Rina. Rina gives you another option. This unlocks Rina's 6th gallery scene. Not sure if it's repeatable anywhere else but the gallery.
Note that the computer has a number of scenes that you can't find anywhere else in game once you've progressed past certain story beats.