Tori no sorane wa

After the sudden death of their parents, Haru and his twin sister, Sora move to the countryside. There, Haru encounters several of the residents, some of whom are old friends like Nao, but Sora stays at home, refusing to go to school even as Haru starts attending. Realizing that Haru is growing more and more distant, Sora goes to Haru's room at night and appeals to Haru as she removes her clothes.