Promise (S01E04)

As Tsukasa waits for Nasa to return home, a young girl named Chitose, who calls her "Nee-sama" confronts her. Chitose asks for Tsukasa to come home with her, and after being ignored, encounters Nasa. He tries to cheer her up, but after learning that Nasa is the one married to Tsukasa, Chitose's attitude suddenly changes. As Nasa tries to explain, Chitose shoves him into a black car that then drives away. (Crunchyroll)