Anime News Network is reporting that Netflix will debut the Lost Song original anime project outside of Japan on September 30, 2018. Netflix is currently listing the September 30, 2018 release date on its Media Center website.
Netflix Japan began streaming the project on March 31, 2018, and new episodes stream weekly on Saturdays. The series also began airing on television in Japan on April 7, 2018.
The official website for Lost Song had listed that the anime would premiere outside Japan in Summer 2018.
Source: ANN