Rika adventures with Aoi!
I'm surprised that she took the effort to bring Aoi to Shikoku by herself. It must be a handful for someone like her, who's usually reserved, to have to take care of such an excited child like Aoi must be exhausting. But it must be worth it to, Aoi looks pretty cute.
Aoi really knows her trains, so she must have been so sad that she couldn't take the trip. I like that their father allowed them to take the trip, but shouldn't she at least know her sister's name?
Ritsu's sad, because her ex is thanking her for raising Rika right, but she didn't even do that.