UTSUBORA - THE STORY OF A NOVELIST

The story begins when Aki Fujino, a beautiful girl who the novelist Mizorogi knew, dies under mysterious circumstances. Then a girl appears before Mizorogi, and although she introduces herself as Aki's twin sister Sakura, her true identity is a complete mystery. As Mizorogi's past ties with Aki come to light, people begin to suspect him of plagiarism. Mizorogi's life spirals deeper into darkness as his editor and the police probe further into Aki's death and Mizorogi's connection with her. (Source: Anime News Network) — Description from AniList community (anilist.co).