Ane no Shinyuu, Watashi no Koibito.

"Embracing these feelings that are mine and mine alone." It's a story about the love between the novelist Sena and her sister's best friend, Kiku. Sena harbors a platonic love for her own sister, but one day her sister introduced her to a girlfriend, and she felt a sense of loss. Since then, Sena tried to keep her distance from her sister, but she couldn't bear the loneliness and couldn't leave. Meanwhile, her sister decided to work abroad, leaving Sena alone again. Then her sister's best friend, Kiku, comes to Sena's house constantly to see her.