On June 17, 2020, it was reported that GFriend would come back on July 13 with a new mini-album titled 回:Song of the Sirens.

A source also reported that: "GFriend recently wrapped up filming the music video for their title track.

[5] On June 28, the group released a teaser video titled "A Tale of the Glass Bead: Butterfly Effect" through Hybe Corporation's official YouTube channel.

[6] On June 30, GFriend released the first set of concept photos titled "Broken Room".

[12] On July 10, the first teaser of the music video for their lead single "Apple" was uploaded on Hybe Corporation’s YouTube channel.