Replying...
Intro. After the sudden death of their parents, HAfter the sudden death of their parents, Haruka and his twin sister Sora move to the house formerly inhabited by their late grandfather, in a small rural village they often visited as children. There, Haruka encounters several of the residents, some of whom are old friends, but Sora stays at home, refusing to go to school even as Haruka starts attending. Realizing that Haruka is growing more and more distant and slipping from her grasp, Sora goes to Haruka's room at night and appeals to Haruka as she removes her clothes… Sora asks Haruka to take her measurements so she can have a uniform made and finally starts attending school with Haruka, though she is disappointed to find that she and Haruka are in different classes. Besides showing hints of a romantic attraction to Haruka, and mild jealousy, she is mostly irrelevant in these two routes. She eventually grows to accept both Kazuha and Akira as partners for Haruka, in their respective routes.

Sora Kasugano

@Ace